National Academy of Modern Science Pattoki: Physics 2nd Year PAST PAPER CHAPTER WISE

Physics 2^nd Year

Past paper Chapter Wise

Electrostatics

Q-1. Encircle the correct answer of the following.

1) The value of permittivity of free space b/w two point charges

(a) 9x10¯¹² C²N¯¹m¯² (b) 8.85x10¯¹² C²N¯¹m¯² (c) 6.62x10¯¹² C²N¯¹m¯² (d) 1.0006 C

2) The value of relative permittivity for all dielectrics other than air or vacuum is always

(a)Less than unity (b) greater than unity (c) equal to unity (d) zero

3) If the distance b/w two charged bodies is halved then force b/w them will be

(a) Doubled

(b) Half

(d) Same

Electric charge of 10 µC is 5cm apart from another charge of 20µC.The force b/w the in Newton

(a) 0.072 N

(b) 720 N

(d) 72000 N

An electric field cannot deflect

(a) X-ray

(b) α- Particle

(d) electron

The electric intensity at infinite distance from a point charge is

(a) Zero

(b) infinite

(d) +ve

One joule is equal to

(a) 1.6x10^-19 ev

(b) 1.6x10^-11 ev

Three capacitors of capacitance 1F, 2F, 4F are connected in series. The equivalent capacitance is

(a) 1 F

(b) 2F

(d) 7F

Electron volt is the unit of

(a) P.D

(b) Electric Energy (c) Power

(d) Capacitance

10)

The charge on the droplet in Milliken experiment is calculated by the formula

(a) q = d/mgd

(b) q = mg/dv

(d) q = vm/gd

11)

If a dielectric is inserted b/w the plates of a charged capacitor, its capacitance

(a) Increase

(b) decrease

11)

If a dielectric is inserted b/w the plates of a charged capacitor, its capacitance

(a) Increase

(b) decrease

12)

Farad is defind as

(a) C/v

(b) A/v

(d) J/C

13)

The SI unit of electric flux is

(a) Nmˉ¹C

(b) NmCˉ¹

(d) Nm²Cˉ

14)

If a charged body moved against the electric field it will gain

(a) P.E

(b) K.E

(d) Electric P.E.

15)

A closed circuit contains two equal and opposite charges. The net electric flux from the surface will be

(a) Negative

(b) Positive

(d) Zero

16)

The quantity ∆V/∆r is called

(a) Electric potential

(b) Electric energy (c) Potential barrier

(d) Potential gradient

17)

The fact that electric field exist in space around an electric charge is

(a) Electric property

(b) Gravitational field

18) One coulomb charge is carried by

	(a) 6.2 x 10¹⁸	(b) One electron					(c) 1.6 x 10^-19	(d) None
19)	The electric intensity near an infinite plate of positive charge will be
	(a) q/ɛ₀	(b) σ/2ɛ₀		(c) q/A			(d) None
20)	One electron volt is equal to
	(a) 6.25 x 10¹⁸ J	(b) 6.25 x 10^-18 J				(c) 1.6 x 10^-19 J (d) 1.6 x 10¹⁹ J.
21)	Presence of dielectric always
	(a) Increases the electrostatic force					(b) Reduces the electrostatic force
	(c) Does not affect the electrostatic force						(d) Double the electrostatic force
22)	For the computation of electric flux the surface area should be
	(a) Flat	(b) Curved				(c) Inclined		(d) Spherical
23) An inkjet printer uses__________ in its operation.
	(a) Positrons		(b) Neutrons		(c) An electric charge			(d) Photons
24)	It is required to suspend a proton of charge q and mass m in an electric field. The strength of field must be
	(a) E = mg/qv		(b) E = q/mg		(c) E = mg/q			(d) E = qvsinθ/q
25)	If medium b/w the charges is not free space then electrostatic force will be
	(a) Increase		(b) Decrease		(c) remain the same				(d) None

26) Equation ϕ = E.A is applicable to the surface

	(a) Spherical	(b) Cylindrical		(c) Conical	(d) Flat
27)	Force per unit charge is called
	(a) Electric flux	(b) Electric Intensity		(c) Electric potential
28)	When some dielectric is inserted b/w the plates of a capacitor, then its capacitance
	(a) Increased	(b) Decreased		(c) Zero
29)	Which of the following is taken as the measure of electric filed intensity?
	(a) F/A	(b) ϕ_e/A	(c) qA/ϕ_e	(d) ϕɛ₀/A
30)	The concept of electric field lines is introduced by
	(a) Coulomb	(b) Faraday	(c) Einstein
31)	Two opposite point charge of same magnitude separated by distance 2d, electric potential mid-way b/w them is
	(a) 1 V	(b) 2 V	(c) Zero	(d) V/2
32)	The expression for energy stored in a capacitor is given by
	(a) E = CV²	(b) E = (½) CV²		(c) E = (1/2) C²		(d) E = (1/2) C²V²
33)	The unit of electric charge is
	(a) Volt	(b) Henry	(c) Coulomb		(d) Weber

Q-2. Write short answers.

1) Electric lines of force never cross .why?

2) Suppose that you follow an electric field line due to +ve charge. Do electric field and potential increases or decreases?

3) If a point of charge ‘q’ of mass ‘m’ is released in non-uniform electric field, will it make rectilinear motion?

4) How can you identify which plate of capacitor is positively charged?

5) What will be the force on a positive charge when placed b/w parallel plates with similar and equal charges?

6) State (i) Gauss’s law (ii) electron volt

7) Define dielectric constant for insulators and mention its unit.

8) The time constant of a series RC circuit is t = RC. Verify that an Ohm times farad is equivalent to second?

9) Define time constant and give its formula.

10) A parallel plate capacitor of capacitance C is charged using a battery of emf V_0. After the capacitor is charged, the battery is removed and the distance b/w the capacitor is doubled. Find the new energy stored.

11) Compare electric and gravitational forces.

12) Prove that electric intensity at any point inside hollow charged sphere is zero.

13) What is difference b/w electric potential energy and electric potential at any point of an electric field?

14) Define eV and find its relation with Joule.

15) Does there exist any electric field inside a hollow charged shell? Prove your answer. How can a

16) metal body act as electrostatic shielding for electronic devices?

17) Show that N/C = V/m

Q-3 (a). Define Gausses law and apply it to calculate electric intensity due to infinite sheet of charge.

(b) Two point charges q1 = 16µC and q2 = 4µC are separated by a distance of 3m. Find a spot on line

where electric field is zero?

Q-4 (a)Find an expression for energy stored in a capacitor also find energy density. OR

What is capacitor and its capacitance? Discuss the factors upon which capacitance of capacitor

depends. Obtain the expression for dielectric constant.

(b) A capacitor has a capacitance of 2.5x10-8 F. In the charging process electrons are removed from one Plate and placed on other one. When the potential difference b/w the plates is 450 v, how many electron have been transferred?

Q-5 (a) How Milliken’s method can be used to determine the charge on electron? OR

Define absolute potential and derive an expression for the potential at a certain point due to a point charge.

(b) A particle having a charge of 20 electrons on it falls through a potential difference of 100v. Calculate the energy acquired by it in electron volt.

Current Electricity

Q-1. Encircle the correct answer of the following.
1)	One Coulomb per second is equal to
	(a) One volt	(b) One Ampere	(c) One Watt	(d) One Ohm
2)	The resistance of a meter cube is called
	(a) Conductivity	(b) Permittivity	(c) Resistivity	(d) Permeability
3)	The SI unit of temperature coefficient of resistivity is
	(a) ohm-meter	(b) 1/K	(c) K	(d) Ohm-K
4)	Three resistance 2 Ω, 4 Ω and 8 Ω are connected in parallel, the equivalent resistance is
	(a) 14 Ω	(b) 8.0 Ω	(c) 1.14 Ω	(d) 2 Ω
5)	Heat generated by 100 watt bulb in 2 hr is
	(a) 100 J	b) 2 x 107 J	(c) 7.2 x 105 J	(d) 7.2 x 104 J
6)	A gold band shows a tolerance of
	(a) ± 10 %	(b) ±7 %	(c) ± 5 %	(d) ± 20 %

7) The apparatus used to compare the emf of two cells is

(a)Wheat Stone Bridge (b) Galvanometer (c) Potentiometer (d) Ammeter

8) Which of the following metal has lowest temperature coefficient?

(a) Silver (b) Copper (c) Aluminum (d) Iron

9) The resistance of the conductor increases with the increase in its

(a) Area (b) Diameter (c) Length (d) None

10) The temperature at which resitivity falls to zero

(a)Lowest temperature (b) Critical temperature (c) Absolute zero temperature (d) None above

11) Watt-hour measure

(a) Current			(b) Electrical energy			(c) Power		(d) Voltage
12)	In Carbon resistor, what is the value of violet color?
(a) 6		(b) 7	(c) 8		(d) 9
13)	Which equation represents the maximum output power?
(a) P = E²/4R			(b) P = E²/4r		(c) P = E²/4R²			(d) P = E²/4r²
14)	Power of an electric generator of voltage (V) and driving current (I) is
(a) P = VI			(b) P = I²R		(c) P = V²/R		(d) All of these
15)	Ceramic materials exhibit super conductivity at
(a) 0⁰ C		(b) 273 K		(c) 60 K		(d) 30 K
16)	Which electric bulb has least resistance?
(a) 60 watts			(b) 100 watts		(c) 200 watts			(d) 500 watts
17)	Tolerance of silver band is
(a) ± 10 %		(b) ±15 %			(c) ± 20 %		(d) ± 25 %
18)	In gases the charge carriers are
(a) Free electrons			(b) Holes		(c) Protons		(d) Electrons and ions

19) Two current carrying conductors are placed parallel to each other then

a) They attract each other for same direction of currents.

b) The attract each other for opposite direction of currents.

c) They repel each other for same direction of currents

d) No force is present b/w them.

20) The substance having negative temperature coefficient is

(a) Carbon (b) Iron (c) Tungsten (d) Gold

21) The resistivity at a given temperature depends upon

(a) Area (b) Length (c) Nature of material (d) All

22) Kirchhoff’s first rule is a manifestation of law of conservation of

(a) Mass (b) Energy (c) Charge (d) KE

23) If the resistance of 500 ohms has fourth band of silver then its upper maximum resistance will be

(a) 600 Ohm (b) 550 Ohm (c) 450 Ohm (d) 400 Ohm

24) The power output of lamp is 6 W. how much energy does lamp give out in 2 minutes

(a) 3 J (b) 12 J (c) 120 J (d) 720 J

25) The proportionality constant b/w current and potential difference is

(a) P (b) R (c) K (d) 1/R

Q-2. Write short answers.

1) Why does the resistance of conductor rise with temperature?

2) Explain why the terminal potential of a battery decreases when the current drawn from it is increased?

3) The resistance of an iron wire at 0 C° is 1 x 104 Ω. What is the resistance at 500 C° if for Iron α = 5.2 x 10-3 K−¹

4) Why a thin region of a light bulb filament has more possibility to burn than thicker one?

5) What is potentiometer? How it is used to compare the emf of two cells.

6) Under what condition the terminal P.D. is greater than emf of the battery?

7) Do bends in wire affect its electrical resistance?

8) Why voltmeter resistance should be very high?

9) Does filament of a bulb obey Ohm’s law?

10) What is rheostat? Describe its uses?

11) Write the heating effect of current.

12) Define electric power. Obtain the maximum power equation OR (What is maximum power output theorem? Drive its formula).

13) What is temperature coefficient of resistance and resistivity?

14) Define conventional current.

15) How many are the number of electrons in one coulomb charge?

Q-3 (a). What is resistivity and conductivity? Name their units. How resistivity depends upon temperature?

(b). A rectangular bar of iron is 2.0 cm by 2.0 cm in cross section and 40 cm long. Calculate the

resistance if resistivity of iron is 11 x 10-8 Ohm-meter.

Q-4 (a). Define Kirchhoff’s current and voltage rule. How it can be applied to determine the

unknown resistance through Wheatstone bridge?

OR Determine the electric power dissipated in a current carrying resistor .

(b). 1.0 x 107 electrons pass through a conductor in 1 µs.Find the current in ampere flowing through

the conductor. Electron charge is 1.6 x 10-19 C ?

Q-5 (a) State and explain Ohm’s law. Describe Ohmic and non-Ohmic materials also what is resistance and

its units.

(b) The resistance of an iron wire at 0⁰ C is 1 x 10⁴ ohm. What is the resistance at 500 500⁰ C if the

temperature coefficient of iron is 5.2 x 10³ K^-1?

Electromagnetism

Q-1. Encircle the correct answer of the following.

1)	The unit of magnetic flux density is
	(a) Tesla	(b) Farad	(c) Joule	(d) Watt
2)	An ammeter is a galvanometer with
	(a) High resistance	(b) Low resistance	(c) Zero resistance	(d) None
3)	The value of shunt resistance, Rs to convert galvanometer into ammeter is
	(a) Rs = IgRg/I+Ig	(b) Rs = IgRg/I-Ig
	(c) Rs = Ig+Rg/IgRg	(d) Rs = V/Ig-Rg

4) A charged particle is projected at an angle into a uniform magnetic field. Which of the

	following parameters of the charged particle will be affected by the magnetic field
	(a) Energy	(b) Momentum	(c) Speed	(d) Velocity
5)	A charge particle moving in a magnetic field experiences a force given by
	(a) F=v.B/q	(b) F=V x B/q	(c) F=qv x B	(d) F= qv . B
6)	The magnetic field inside a current carrying solenoid is
	(a) Non- uniform	(b) Uniform	(c) Weak	(d) None

7) If a current flows from top to bottom through a wire then direction of lines of force would be

(a) Parallel to wire (b) Perpendicular to wire

8) An avometer can also be called

(a) Digital ammeter (b) Digital CRO (c) Digital voltmeter (d) Multi-meter

9) The magnet field at point due to current carrying conductor is directly proportional to

(a) Current passing through conductor				(b) resistance of the conductor
10)	The brightness of the spot on CRO screen is controlled by
(a) Cathode		(b) Anode		(c) Grid	(d) Plates
11)	The unit of magnetic flux is
(a) Nm^-1A^-1		(b) NmA^-1		(c) Nm^-1A	(d) Wb.m^-2
12)	The deflecting couple in a galvanometer is given by
(a) NI/AB		(b) NAIB	(c) ABI/N		(d) None
13)	The anode in the CRO is
(a) Control no of waves			(b) Control brightness		(c) Accelerate and focus beam

(d)At negative potential wrt cathode.

14) If the charge is free to move in electric field then acceleration will be

	(a) qE/m	(b) qEm	(c) q/Em			(d) m/qE
15)	CRO works by deflecting a beam of
	(a) Neutrons	(b) Protons		(c) Electrons		(d) positrons
16)	The magnetic force is simply a
	(a) Reflecting force	(b) Deflecting force			(c) Restoring force (d) None
17)	Work done on charged particle moving in magnetic field will be
	(a) Maximum	(b) Minimum			(c) Zero	(d) Negative

18) If number of the turns becomes doubled but length remains same then magnetic field in the solenoid be

(a) Half (b) Double (c) Remain same (d) Zero

Q-2. Write short answers of the following questions.

1) What are the uses of CRO?

2) How can you use a magnetic field to separate isotopes of a chemical element?

3) What is Lorentz force and how can it be formulated

4) What is stable galvanometer?

5) Why voltmeter should have a very high resistance?.

6) Why does the picture on TV screen become distorted when a magnet is brought near to screen?

7) Why B is non-zero outside the solenoid?

8) Why the resistance of an ammeter should be very low?

9) Define sensitivity of a galvanometer?

10) Distinguish b/w magnetic flux and flux density?

11) What is stable dead beat galvanometer?

12) Briefly explain the function of filament and grid in CRO.

13) Describe the right hand rule to find the direction magnetic field.

14) What is phantom bar magnet?

15) What is lamp scale arrangement in galvanometer?

16) What is the function of sweep generator in CRO?

17) How can you convert a galvanometer into ammeter?

Q-3 (a). State Ampere law. Apply it find B due to current carrying solenoid

(b). what current should pass through a solenoid 0.5 m long with 10000 turns of copper wire so that it

will have a magnetic field of 0.4 T. (µo = 4π x 10-7 WbA−¹m−¹).

Q-4 (a). Find an expression for force on a moving charge in a magnetic field in the form of F = q(v x B )

(b).How fast a moving proton move in a magnetic field of 2.5 x 10-3 T such that magnetic force is equal

to its weight ?

Q-5 (a) what is galvanometer? Write its principle, construction and working.

(b)Alpha particle ranging in speed from 1000 m/s to 2000 m/s enters into a velocity sector where the

electric intensity is 300 V/m and magnetic induction is 0.20 T. Which particle will move undirected

through the field?

Electromagnetic Induction

Q-1. Encircle the correct answer of the following.

1) The direction of induced emf is so as to oppose the change which causes the current. This is

	(a) Coulomb’s law	(b) Ampere’s law	(c) Faraday’s law	(d) Lenz’s law
2)	Si unit of mutual induction is
	(a) Coulomb	(b) Joule	(c) Ampere	(d) Henry
3)	Self inducting coils are called
	(a) Insulators	(b) Inductors	(c) Conductors	(d) None
4)	Back emf of motor which is just started
	(a) Zero	(b) constant	(c) greater	(d) None
5)	Transformer works on the principle of
	(a) Mutual Induction	(b) Back emf	(c) Self Induction	(d) None

6) A rod of unit length is moving at 30° through a magnetic field.If velocity of rod is 1 m/s the motional emf is

(a) 0.25 V (b) 0.5 V (c) 1 V (d) 0.1 V

7) If velocity of moving conductor through a magnetic field is zero then its motional emf is

(a) Zero (b) qvB (c) ILB (d) vBLSinθ

8) A metal rod of 25 cm is moving at the speed of 0.5 m/s in a direction perpendicular to a 0.25 T magnetic

field. The emf produced in the rod is

(a) 3.13 x 10-2 V (b) 3.13 V (c) 3.13 X 10-3 V (d) 3.13 x 10-5 V

9) The turn ratio of a transformer is 50.A current of 20 A is passed through its primary coil at 220 Voltage in

secondary is

(a) 1100 V (b) 1110 V (c) 1000 V (d) 11000 V

10) A DC motor operates at 240 V and has a resistance of 0.5 ohm. When motor is

running at normal speed, the armature current is 15 A. Back emf in the armature is

(a) 2300 V (b) 232.5 V (c) 230.5 V (d) 300 V

11) According to faraday law, emf induced in the ckt depends upon

(a) Maximum magnetic flux (b) Rate of change of magnetic flux

12) Eddy currents set up in a direction

(a) Parallel to flux (b) Antiparallel to flux

13) An inductor may store energy in its

(a) Coil (b) Electric field (c) Magnetic Field (d) Both A and B

14) Potentiometer can be used as

(a) Ohm meter (b) Ammeter (c) Galvanometer (d) Potential divider

15) If motor is overloaded, then magnitude of back emf

(a) Increase (b) Decrease (c) Constant (d) Become zero

16) In equation ɛ = -VBLSin θ, θ is angle b/w

(a) I and B (b) V and B (c) V and L (d) L and b

17) A charge q is placed stationary in a region where both electric and magnetic field are present. The charge

will experience

(a) Both electric and magnetic forces (b) Electric force (c) Magnetic force (d) None

18) Lenz law is in accordance with law of conservation of

(a) Momentum (b) Charge (c) Energy (d) Angular momentum

19) If magnetic field is doubled then magnetic energy density becomes

	(a) Four times	(b) Two times		(c) Three times		(d) Six times
20)	As motor speeds up, the back emf
(a) Increase		(b) Decrease	(c) Constant			(d) Become zero
21)	The winding of the electromagnet in motor are usually called
(a) Magnetic coils		(b) Field coils	(c) Electric coils		(d) Electric –o- magnetic coils
22)	Commutator was inverted in
(a) 1736		(b) 1834	(c) 1935	(d) 1885

Q-2. Write short answers of the following questions.

1) Does the induced emf depends upon the resistance of the circuit?

2) Can a DC motor be turned into DC generator?

3) Four unmarked wires are emerged from a transformer. What steps would you take to determine the turn ration?

4) Can a step up transformer increase power level?

5) Show that emf and ∆ф/∆t has same units?

6) Does emf always act to decrease the magnetic flux through the coil?

7) How would you position a flat loop of wire in a changing magnetic flux so that there is no emf induced in the loop?

8) Can a motor be used to drive an generator with the output from generator being used to operate motor?

9) Define Faraday law of electromagnetic induction.

10) Define (a) Lenz law (b) Self induction

11) Why the voltmeter should have very high resistance?

12) Write two methods to change the flux for electromagnetic induction.

13) Explain working of heater that works on the principle of electromagnetic induction.

14) How can we improve the efficiency of transformer?

15) Distinguish between slip rings and split rings.

16) Write down the factors upon which mutual inductance depends.

Q-3 (a). Define motional emf.Find an expression for motional emf?

(b). A circular coil has 15 turns of radius 2 cm each. The plane of the coil lies at 40° to a uniform

magnetic field of 0.2 T. If the field is increased to 0.5 T in 0.2 s, find the magnitude of induced emf.

Q-4 (a). Define and explain mutual induction?

(b). When the current through a coil changes from 100 mA to 200 mA in 0.005 s an induced emf of 40

mV is produced in the coil (a) what is the self inductance of the coil? (b) Find the increase in energy

stored in the coil?

Q-5 (a) Find an expression for energy stored in an inductor. Also find expression for energy density. What is

ac generator? Describe its principle, construction. Also derive formula to calculate the emf induced in

the loop.

b)An emf of 5.6 v is induced in a coil while the current in a nearby coil is decreased from 100 A to 20 A in

0.02 s. What is the mutual inductance of two coils? If the secondary has 200 turns, find the change in

flux during this interval?

Alternating Current

Q-1. Encircle the correct answer of the following.

1) Capacitance of resonance circuit of frequency 1000 kHz with an inductor of 5 mH is

(a) 5.09 pF (b) 509 pF (c) 500 pF (d) 5090 pF

2) A 100 µF capacitor is connected to an alternating voltage of 24 V and frequency 50 Hz. Its reactance is

	(a) 31.8 Ω	(b) 30.0 Ω		(c) 310 Ω	(d) 318 Ω
3)	An AC voltmeter reads 250V.If its frequency is 50 Hz then its peak value is
	(a) 353.5 V	(b) 350.5 V		(c) 300 V	(d) 3000 v
4)	The output voltage of AC generator
	(a) Remains constants		(b) Varies linearly with time
	(c) Varies sinusoidally with time		(d) None
5)	The wave form of alternating voltage is
	(a) Cosine wave	(b) Sine wave		(c) Linear wave	(d) None
6)	The average vale of V² and I² is the
	(a) Instantaneous value	(b) Absolute value		(c) RMS value	(d) P - P Value
7) Inductance and capacitance behave oppositely as a function of
	(a) Time	(b) Amplitude		(c) Frequency	(d) None

8) If an inductor of 2.0 H has a reactance of 600 Ω, its frequency is

(a) 12 Hz (b) 24 Hz (c) 36 Hz (d) 48 Hz

9) At resonance frequency the circuit impedance is

(a) Minimum (b) Maximum (c) Zero (d) Negative

10) In three phase AC generator, there are three coils inclined at

(a) 30° to each other (b) 60° to each other (c) 90° to each other (d) 120° to each other

11) If capacitance of the LC ckt is made four times, then frequency of the ckt becomes

(a) Twice (b) One half (c) Four times (d) None

12) The r.m.s value of the current is given by

(a) I0/ (b) I0 (c) 2 I0 (d) I0/2

13) At what the frequency will an inductor of 1 H have a reactance of 500 ohm?

14) In ac ckt at resonance, the phase difference b/w current and voltage is

	(a) 90⁰		(b) 180⁰	(c) 0⁰	(d) 360⁰
15)15)	The frequency of AC used in Pakistan is
	(a) 60 Hz		(b) 50 Hz	(c) 100 Hz			(d) 120 Hz
16)	The highest value reached by voltage or current in one cycle is called.
	(a)Peak to peak value			(b) Peak value			(c) Instantaneous value			(d) rms value
17)	At higher frequency the current through a capacitor of AC ckt will be
	(a) Large		(b) Small	(c) Infinite		(d)		Zero
18)	The phase at negative peak will be
	(a)	л/2	(b) л/3	(c) 3л/2	(d) л
19)	The process of combining the low frequency signal with high frequency carrier wave is called
	(a)	Wave transmission		(b) Modulation				(c) Resonance	(d) Beats
20)	The basic ckt element in AC which control current is
	(a)	Resistor	(b) Capacitor		(c) Inductor			(d) All these
21) The impedance of the RLC series ckt is
	(a)	Z = √ [ R² + (X_L –X_C)²]		(b) √ [ R² + X_L² ]				(c) Z = R	(d) √ [ R² + X_C

22)	The capacitive reactance to pure Dc is
	(a) Zero	(b) Infinite		(c) Variable		(d) Equal to X_L
23) In capacitor
	(a) I leads V by л/2		(b) I lags V by л/2			(c) I leads V by л	(d) Both are in phase
24)	The velocity of an oscillating charge as it moves to and fro along a wire is
	(a) Changing		(b) Constant	(c) Infinite		(d) Zero
25)	Choke consumes extremely small
	(a) Current	(b) Charge		(c) Power		(d) Potential
26)	High frequency radio wave is called
	(a) Matter wave		(b) Carrier wave		(c) Electromagnetic wave		(d) X ray

Q-2. Write short answers of the following questions.

1) AC has rms value of 10 A. What is its peak value?

2) How many per second an incandescent lamp will reach maximum brilliance when connected to 50 Hz A.C.

3) Name the device that will permit the flow of A.C. but oppose the flow of D.C..?

4) Define choke and give its uses.

5) In R – L circuit, will the current lag or lead the voltage. Illustrate your answer by a vector diagram.

6) How does doubling the frequency affect the reactance of an (a) Inductor? (b) Capacitor.

7) How the reception of particular radio station is selected on your radio set?

8) Why alternating current keeps on changing its direction with time? Explain.

9) When 10 V are applied to an AC circuit, the current flowing through it is 100 mA.Find its impedance.

10) Define power. What is power factor in AC circuit?

11) Show graphically the phase relationship b/w current and voltage across the inductor.

12) What are electrical oscillators? How do they play their part in metal detectors?

13) Compare FM and AM radio waves.

14) At what frequency will an inductor 0f 10 H have a reactance of 500 ohm?

15) What is reactance? Prove that the capacitive reactance [X_c = 1/ωC] and inductive reactance [X_L = ωL] have the same units equal to that of resistance R i.e Oh

Q-3	(a).	Discuss A.C. through resistor.
	(b). An alternating current is represented by the equation I = 20Sin100πt. Compute		its frequency, maximum
		and rms value of current..
Q-4	(a).	Discuss R.C. series circuit. Find its impedance and draw its impedance diagram.
	(b).	A circuit has an inductance of 1/π H and resistance of 2000 Ω. A 50 Hz A.C. is	supplied to it. Compute
		the reactance and impedance offered by the circuit.
Q-5	(a)	Discuss A.C through a capacitor .Draw and explain its graph. Define reactance	of a capacitor.

(b) A 10 mH, 20 Ω coil is connected across 240 V and 180/π Hz source. How much power is

dissipated?

Physics of Solids

Q-1. Encircle the correct answer of the following.

1)	A solid having regular arrangement of molecules throughout its structure is called
	(a) Polymeric solid	(b) Perfect Solid	(c) Crystalline Solid (d) Amorphous Solid
2)	Curie temperature for iron is
	(a) 1050 Cº	(b) 750 Cº	(c) 850 Cº	(d) 650 Cº
3)	Ability of the body to original shape is called
	(a) Strain	(b) Stress	(c) Plasticity	(d) Elasticity
4)	The SI unit of Stress is
	(a) Nm¯²	(b) Nm¯¹	(c) Nm²	(d) Nm
5)	Good conductors have conductivities of the order of
	(a) 10-5 ( Ωm )¯¹	(b) 107 ( Ωm )¯¹	(c) 10-9 ( Ωm )¯¹	(d) 108 ( Ωm )¯¹
6)	With rise of temperature, the conductivity of semiconductor
	(a) Increases	(b) Decreases	(c) Remains Same	(d) None
7)	The fist superconductor was discovered in
	(a) 1990	(b) 1960	(c) 1911	(d) 1831
8)	The source of magnetism of atom is the
	(a) Electrons	(b) Protons	(c) Neutrons	(d) Photons
9)	Domains contain nearly
	(a) 108 to 109 atoms		(b) 10¹² to 1016 atoms
	(c) 1015 to 1020 atoms		(d) none

10) A 5.0 meter long copper wire is subjected to stretching force and its length increases by 10 cm.The tensile

strain is

(a) 0.02 m			(b) 0.0143 cm			(c) 0.20 cm		(d) 2.0 m
11)	As mass number increases, which of the following does not change?
(a) Mass		(b) Volume			(c) Density			(d) Binding energy
12) In Ge sample traces of Ga				are added as impurity. The resulting sample would behave like
(a) A conductor			(b) A p-type semiconductor					(c) A N-type semiconductor		(d) An insulator
13)	What are the substances called which undergo plastic deformation until they break
(a) Brittle substance				(b) Ductile		(c) Amorphous substance			(d) Polymeric substance
14)	Once the resistance of the material is dropped to zero, the
(a) Energy is dissipated				(b) Current is dissipated				(c) Energy and current both are dissipated
(d)	Energy and current both are not dissipated
15)	N-type germanium is obtained by doping intrinsic germanium with
(a) Tetravalent impurity atom					(b) Trivalent impurity atom
(c) Pentavalent impurity atom					(d)	hexavalent impurity atom
16)	The ratio of applied stress to volumetric strain is called
(a) Young’s modulus				(b) Shear modulus			(c) Bulk modulus		(d) tensile strain
17)	When a stress changes the shape of a body, is called
(a) Volumetric stress				(b) Shear stress			(c) Tensile stress		(d) Compressional stress
18)	How many crystal system are there on the basis of geometrical arrangement of atoms
(a) 3		(b) 4	(c) 5			(d) 7
18)	The ability of a body to return to its original shape is called
(a) Plasticity			(b) Elasticity			(c) Stress		(d) Strain
19)	Which of the following has the least hysteresis loop area
(a) Steel		(b) Wrought iron				(c) Soft iron		(d) Cobalt

20) Which of the following is crystalline solid

(a) Glassy solids (b) natural rubber

(c)Polystyrene (d) Zirconia

21) The substance which have partially filled conduction band are called

(a) Insulator (b) Semi-conductor (c) Conductor (d) Super conductors

22) Which type of impurity is to be added to the semiconductors to provide holes?

(a) Monovalent (b) Trivalent (c) Tetravalent (d) Pentavalent

Q-2. Write short answers of the following questions.

1) Distinguish b/w conductors, insulators and semiconductors with the help of energy band theory.

2) Draw stress- strain curve for a ductile material and then define the terms elastic limit, yield point and ultimate tensile stress.

3) Write a note on super conductors.

4) Why energy dissipated per cycle for steel is greater than iron?

5) Define stress and strain..

6) Define crystalline and amorphous solids.

7) Distinguish b/w valence band and conduction band.

8) What do you mean by Curie temperature?

9) A 1.25 cm diameter cylinder is subjected to a load of 2500 kg. Calculate the stress on the bar in mega Pascal.

10) What is behavior of silicon at 0 Cº.

11) Define unit cell and give the number of basic crystal systems.

12) Give the order of conductivity of conductors and semiconductors.

13) Distinguish b/w donor atom and acceptor atom.

14) Define elastic limit.

15) What are superconductors? Why are they preferred? Give names of two devices where superconductors are applied.

16) Explain the existence of magnetic domains in ferromagnetic material.

17) What is meant by hysteresis loss? How is it used in the construction of a transformer?

18) What is meant by hysteresis loss?

Q-3 (a). What is meant by strain energy? How it can be determined from force – extension graph?

(b). The length of steel wire is 1 m and its cross sectional area is 0.03 x 10-4 m². Calculate the work

done in stretching the wire when a force of 100 N is applied within the elastic region. Young’s

modulus of steel is 3 x 10¹¹ Nm¯².

Q- 4 (a) What are semiconductors? How P-type and N-type materials are form.

What is doping? Describe the formation of N type and P type semiconductors.

(b). 1 m copper wire is subjected to stretching force and its length increases by 20 cm. Calculate the

tensile strain and percent elongation which the wire undergoes.

Q-5 (a) What is meant by para, dia and ferromagnetic substances. Give example for each..

(b) What stress would cause a wire to increase in length by 0.01 % if the Young’s modulus of wire is

12x10¹º Pa. What force would produce this stress if the diameter of the wire is 0.56 mm?

Electronics

Q-1. Encircle the correct answer of the following.

1) Depletion region has
(a) Electrons only					(b) Holes only
(c) Neither electron nor holes					(d) Both electrons and holes
2) Device used for the conversion of AC into DC is called
(a) Oscillator			(b) Rectifier		(c) Amplifier		(d) Modulator
3) The potential barrier for Ge at room temperature is
(a) 1 volt			(b) 7 volts		(c) 0.3 volt		(d) 0.7 volt
4) The gain of an inverting amplifier of external resistance R1 = 10 kΩ and R2 = 100 kΩ
(a) -5			(b) -10		(c) -2		(d) 50
5) Two inputs Nand gate with inputs A and B has an output 0 if
(a) B is 0			(b) A is 0		(c) Both A and B are 0		(d) Both A and B are 1
6) The current gain of a transistor ß is given by
(a) ß		= 1/IbIc	(b) ß	= Ib/Ic	(c) ß = Ic/Ib		(d) ß = IbIc
7) Vo/Vi		=
(a) ßRc/rie			(b) ßrie/Rc		(c) ß/rieRc		(d) ßrieRc
8) For a given transistor the ratio of collector to base current is
(a) Constant			(b) Variable		(c) Non constant		(d) None
9) In a given Circuit, the transistor has a collector current of 10 mA and base current of
40 µA. The current gain is
(a) 250			(b) 357		(c) 500		(d) 1000
10)	The color of light emitted by LED depends upon
(a) Its forward bias					(b) Its reverse bias
(c) Semiconductor material used					(d) none
11) In which type of logic gate , the output is one when both inputs are zero?
(a) OR gate			(b) AND gate			(c) NOT gate		(d) NOR gate
12)	Which of the following is NOT basic operation of Boolean variables?
	(a) Yes Operation			(b) NOT operation		(c) AND operation		(d) OR operation
13)	A potential barrier of 0.7 V exist across p-n junction made from
(a) Silicon			(b) Germanium			(c) Indium		(d) Gallium
14)	When PN junction is reversed biased, the depletion region is
(a) Widened				(b) Narrowed		(c) Normal		(d) No change
15)	A PN junction on forward biasing acts as
(a) Capacitor				(b) High resistor		(c) Inductor		(d) Low resistor
16)	The mathematical operation for NOR operation is
(a) X = .B			(b) X =			(c) X = A.		(d) X =
17)	The voltage gain of an inverting OP- amplifier is
	(a) G = 1 -			(b) G = 1+		(c) G -		(d) None
18)	A LED emits light only when
	(a) Reversed biased			(b) Forward biased			(c) Unbiased		(d) None
19)	The base in a transistor is of the order of
	(a) 10^-6 m		(b) 10^-4 m			(c) 10^-3 m	(d) 10^-1 m
20)	The transistors are made from
	(a) Plastics		(b) Metals			(c) Conductors		(d) None

21) The term transistor stand for

(a) Transfer of current (b) Transfer of voltage (c) Transfer of resistance (d) Transfer of charge

22) LED is made form

(a)Silicon (b) Germanium

(d) Gallium arsenide

23) The SI unit of current gain is

(a) Ampere (b) Volt

(d) No Unit

24) LDR id abbreviated for

(a) Light dependent resistance

(b) Light depositing resistance

(d) All of these

Q-2. Write short answers of the following questions.

1) What is transistor? How NPN transistor circuit is drawn in common emitter configuration.

2) What are the applications of a photo diode?

3) What is the principle of virtual ground? Apply it to find the gain of an inverting amplifier.

4) Why charge carriers are not present in depletion region?

5) Why a photo diode is operated in reverse bias?

6) What is light emitting diode?

7) What is leakage current?

8) What are photo voltaic panels?

9) Define (a) logic gate (b) Boolean algebra

10) Draw circuit symbol for NPN and PNP transistor.

11) Draw the symbolic ckt diagram for exclusive NOR (XNOR) gate.

12) Make the ckt diagram of full wave rectification. Also give path of conventional current on it.

13) How does an operational amplifier work as a comparator? Draw its ckt diagram and write down its working conditions.

14) Write down the characteristics of operational amplifier.

15) Draw the ckt diagram of XOR gate and write down its truth table.

16) What is the effect of forward and reverse biasing on the width of reverses biased state.

17) We often see that during day time when it is cloudy, street lights turn ON automatically. Why does it so happen?

Q-3 (a). What is meant by rectification? Explain the action of a semiconductor transistor as half wave

rectification.

(b). The current flowing into the base of a transistor is 100 µA. Find its collector current, emitter current if

ß = 100

Q- 4 (a) Discuss operational amplifier as inverting amplifier.

(b). Write about comparator as night switch.

Q-5 (a) Discuss NPN transistor as an amplifier.

(b) Write a note on forward bias PN junction.

Dawn of Modern Physics

Q-1. Encircle the correct answer of the following.

1) The earth’s orbital speed is

(a) 60 kms¯¹	(b) 50 kms¯¹	(c) 40 kms¯¹	(d) 30 kms¯¹
2) K.E =
(a) (m – m0) c²	(b) (m + m0) c²	(c) (m – m0) c	(d) (m + m0) c
3) The amount of emitted radiation for different wavelengths is
(a) Same	(b) Different	(c) Constant	(d) None

4) The value of Stephen’s constant is

	(a) 8.67 x 10-8 Wm²K-4		(b) 7.67 x 10-8 Wm²K-4
	(c) 6.67 x 10-8 Wm²K-4		(d) 5.67 x 10-8 Wm²K-4
5) In photoelectric effect, the electrons are emitted with
	(a) Same energy	(b) Different energy	(c) Same K.E.	(d) None
6)	The minimum energy require to escape from the metal surface is called
	(a) Potential barrier	(b) Potential function	(c) Work function	(d) None
7)	A photo cell based on
	(a) Pair production	(b) Compton effect	(c) Photo electric effect (d) None
8)	The numerical value of Compton wavelength is
	(a) 2.43 x 10-24 m	(b) 2.14 x 10¯¹² m	(c) 2.43 x 10−¹²m	(d) 2.43 x 1024 m

9) Compton shift is equal to Compton wavelength if scattered X – ray photons are observed at θ =

(a) 90º		(b) 60º	(c) 45º	(d) 30º
10)	The uncertainty principle b/w energy and time is given by
(a) ∆E.∆t ≈ h²		(b) ∆E ≈ ∆th	(c) ∆t ≈ h∆E	(d) ∆E.∆t ≈ h
11)	The relation b/w Rhydberg constant and ground state energy is
(a) RH=Eo/hc		(b) RH= hc/Eo	(c) Eo-RH/hc	(d) RH=Eohc
12)	Reverse phenomenon of photo electric effect is called
(a) Radioactivity		(b) Compton Effect	(c) Zeeman Effect	(d) X ray production

13) In Compton scattering , the change in wavelength is maximum if scattering angle is

(a) 90⁰ (b) 60⁰ (c) 180⁰ (d) 0⁰

14) At what speed would the mass of an electron become double if its rest mass is

(a) 0.5C (b) 0.707 C (c) 0.866 C

(d) 0.99 C

14) How does the results of special theory of relativity been applied to NAVASTAR navigation system?

Dimensional representation of Planks constant is the same as

(a) Gravitational constant (b) Torque (c) Momentum (d) Angular momentum

15) Emission of electrons by metals on heating is called

(a) Secondary emission (b) Field effect (c) Photoelectric emission (d) Thermionic emission

16) in 1905 the special theory of relativity was proposed by

(a) Maxwell (b) de-Broglie (c) Bohr (d) Einstein

17) The momentum of moving photon is

(a) 0 (b) P = hλ (c) P = h/λ (d) P = λ/h

18) If an object moves with speed of light , its mass become

(a) 0 (b) Infinity (c) Same (d) Small

19) Which light photon has least momentum?

(a) Red (b) Blue (c) Yellow (d) Green

20) Every particle has corresponding antiparticle with

(a) Same mass (b) Different mass (c) Opposite charge (d) Same mass but different charge

21) The rest mass energy of an electron-positron pair is

(a) 0.51 Mev (b) 1.02 Mev (c) 1.2 Mev (d) 1.00 Mev

22)	Einstein was awarded Noble Prize in physics in
(a) 1905		(b) 1911	(c) 1918	(d) 1921
23)	Who gave the idea of matter wave
	(a) Plank	(b) de-Broglie	(c) Bohr	(d) Einstein
24)	When platinum wire is heated , it becomes----------- at 500 C⁰?
	(a) White	(b) Green		(c) Yellow	(d) Dull red
25)	Number of electrons emitted in photoelectric effect depends upon
	(a) Intensity of incident light		(b) Frequency of incident light
	(c) Energy of incident light		(d) Wavelength if incident light

Q-2. Write short answers of the following questions.

1) An electron is placed in a box about the size of an atom that is about 1.0 x 10¯¹º m. What is velocity of electron?

2) As solid is heated and begins to glow, why does it first appear red?

3) Is it possible to create a single electron from energy? Explain.

4) We do not notice the de- Broglie wavelength for a pitched cricket ball.

5) Can pair production take place in vacuum?

6) Will bright light eject more electrons from a material than a dimmer light of same color?

7) Define inertial frame of reference.

8) A particle of mass 5 mg moves with speed of 8 m/s. Calculate its de- Broglie wavelength.

9) If we keep on applying force on material object, can it gain the speed of light?

10) What is the mass of 70 kg man in space rocket traveling at 0.8 c from us as measured from earth?

11) Define inertial frame and non inertial frame of reference.

12) What advantages an electron microscope has over an optical microscope?

13) What determines the number of photoelectrons emitted from metal surface and their maximum kinetic energy?

14) What is Compton effect?

15) What are black body radiations?

16) Distinguish b/w general theory of relativity and special theory of relativity.

17) What is photon?

Q-3 (a). State postulates of special theory of relativity. Explain three results of this theory.

(b). X-Rays of wavelength 22 pm are scattered from a carbon target. The scattered radiation being viewed at

85º to the

		incident beam. What is the Compton shift?
Q- 4	(a)	State and explain uncertainty principle. Write two forms of uncertainty principle.
	(b). Yellow light of 577 nm is incident on cesium surface. The stopping voltage is		found to be 0.25 V. Find
		(a)Max. K.E. of photoelectrons (b) Work function of cesium.
Q-5	(a)	Define photo electric effect. Write important results. Explain on the basis of	quantum theory.
	(b) What is the energy of a photon in a beam of infrared radiation of wavelength1240 nm?

Atomic Spectra

Q-1. Encircle the correct answer of the following.

1)	The value of Rydberg constant is
	(a) 1.097 x 10-7 m¯¹	(b) 1.0974 x 107m¯¹	(c) 10.0974 x 10-7m¯¹	(d) None
2)	The diameter of the nucleus is of the order of
	(a) 10¹º m	(b) 10¯¹² m	(c) 10-14 m	(d) 10-16 m

3) Speed of electron in the first Bohr’s orbit is

(a) 2.19 x106 m/s		(b) 3.79 x 106 m/s
(c) 3.19 x 10-6 m/s		(d) 3.19 x 105 m/s
4) The rest mass of x-ray photon is
(a) Infinite		(b) 9.1 x 10-34 kg
(c) 1.67 x 10-27 kg		(d) 1.67 x 10-26 kg
5) Helium – Neon laser discharge tube contains Neon
(a) 25 %	(b) 40%		(c) 15 %	(d) 85 %
6) Laser works on the principle of
(a) Spontaneous emission		(b) Stimulated emission
(c) Both a and b		(d) None
7) X- rays are deflected by
(a) Electric field	(b) Magnetic field		(c) Both a and b	(d) Neither a nor b
8) The potential required to remove completely an electron from an atom is called
(a) Ionization potential		(b) Critical potential
(c) Atomic potential		(d) Excitation potential
9) X- rays are similar in nature to
(a) Alpha rays	(b) Beta rays		(c) Gamma rays	(d) None
10) The Blamer series lies in
(a) Ultraviolet region		(b) Infrared region
(c) Visible region		(d) None
11) The continuous spectrum is due to an effect known as
(a) Bremsstrahlung effect		(b) Compton effect
(c) Photoelectric effect		(d) None
12) The radius of 3^rd Bohr’s orbit in hydrogen atom is greater than 1^st				orbit by factor of
(a) 2	(b) 3		(c)4	(d) 9

13) As per Bohr’s atomic model, a minimum energy required to remove an electron from ground state of doubly

ionized Li-atom is

	(a) 1.51 eV	(b) 13.6 eV	(c) 40.48 eV	(d) 122.4 eV
14)	In which region of electromagnetic spectrum of hydrogen atom, the blamer series lies
	(a) Infrared	(b) Visible	(c) Ultraviolet	(d) Far-ultraviolet
15)	If the ionization energy of hydrogen atom is 13.6 eV, its ionization potential will be
	(a) 13.6 V	(b) 136 V	(c) 3.4 V	(d) None
16)	Which of the following lies in ultraviolet region?
	(a) Lyman series	(b) Balmer series	(c) Pfund series	(d) Bracket series
17)	A positron is antiparticle of
	(a) Proton	(b) Electron	(c) Neutron	(d) Photon
18)	If number of atoms in metastable state E₂ is N₂ and in ground state E₁ is N₁ , then population inversion means
	(a) N₂ =N₁	(b) N₂ <N₁	(c) N₂ >N₁	(d) N₂ /N₁ =E₂ /E₁
19)	Life time of metastable state is
	(a) 10^-8 s	(b) 10^-5 s	(c) 10^-3 s	(d) 10^-2 s

20)	Energy of 4^th orbit in hydrogen atom is
	(a) -2.51 eV	(b) -3.50 eV		(c) -13.6 eV		(d) -0.85 eV
21)	Which is not true for x-rays
	(a) X-rays are not deflected by E		(b) X-rays are polarized		(c) X-rays are EMW.

22) X-rays can be diffracted by grating Production of x-rays is reverse process of

(a) Photo electric effect (b) Compton effect (c) Annihilation (d) Pair production

23) Which is example of continues spectra?

(a) Black body radiation spectrum (b) Molecular spectra

Q-2. Write short answers of the following questions.

1) Do any Bohr’s postulate contradict with classical physics?

2) What is quantum theory?

3) What are advantages of LASER over ordinary light?

4) What are X-rays? Give some properties of X- rays.

5) Write a note on CAT – SCANNER.

6) Write some uses of Laser in medicine and industry.

7) Is energy conserved when an atom emits a photon of light?

8) Find the speed of electron in first Bohr orbit?

9) What is energy in eV of quanta of wavelength 400 nm?

10) How the spectrum of hydrogen can emit many lines when hydrogen contains one electron?

11) How does spontaneous emission is differ from stimulated emission? Draw energy level diagram.

12) Differentiate an orbital electron from free electron.

13) 13)How does kα ray differ from kβ ray?

14) A tungsten target is struck by electrons that have been accelerated from rest through 40 kV potential difference. Find the shortest wavelength of the bremsstrahlung radiation emitted.

15) What is meant by line spectrum? How it can be used for the identification of elements?

16) Explain why laser action could not be occurred without population inversion b/w atomic levels.

17) What are biological effects of X-rays?

Q-3 (a). Write postulates of Bohr’s theory. Derive an expression for radii of quantized orbit.

(b). Calculate longest wavelength in Paschen series.

Q- 4 (a) Explain how X-rays are produced? Write any one use of x-rays.

(b). Compute the shortest wavelength radiation in Balmer series.

Q-5 (a) What is Laser. Write about population inversion and Laser action..

(b)Electron in an X ray tube are accelerated through a potential difference of 000V. If these electrons were

slowed down in a target, what will be the minimum wavelength of X rays produced?

Nuclear Physics

Q-1. Encircle the correct answer of the following.

1)	The protons and neutrons present in the nucleus are called
	(a) Photons	(b) Hadrons	(c) Leptons	(d) Nucleons
2)	Neutrons was discovered by
	(a) Rutherford	(b) James Chadwick	(c) J.J.Thomson	(d) Newton
3)	The speed of α – particles with which they hit the gold foil is about
	(a) 1000 m/s	(b) 2 x 103 m/s	(c) 2 x 105 m/s	(d) 2 x 107 m/s
4)	The building blocks of protons and neutrons are called
	(a) Electrons	(b) Quarks	(c) Ions	(d) Photons
5)	The binding energy per nucleon is maximum for
	(a) Iron	(b) Uranium	(c) Radium	(d) Oxygen
6)	The mass of a proton is equal to
	(a) 1.67 x 10-27 kg	(b) 1.67 x 10¯¹¹kg	(c) 1.67 x 10-34 k	(d) None
7)	1 µ =
	(a) 931 MeV	(b) 931 eV	(c) 0.931 MeV	(d) Both a and b
8)	The unit of Decay constant λ is
	(a) s	(b) eV	(c) s¯¹	(d) Joule
9)	Protons are accelerated by a machine known as
	(a) Accelertron	(b) Cyclotron	(c) Reactor	(d) None

10) The penetration of α – particles

(a) Greater than ß – particles		(b) Equal to ß – particles
(c) Less than ß – particles		(d) None
11)	The half- life of ⁹¹Sr₃₈ is 9.70 hours. What is its decay constant?
	(a) 1.98 x 10^-5 S^-1	(b) 1.6 x 10^-4 S^-1	(c) 2.5 x 10^-5 S^-1	(d) None
12) Leptons are particles that do not expe3rience
	(a) Weak nuclear force	(b) Strong nuclear force	(c) Electric force	(d) Magnetic force
13)	The half-life of a radioactive element is
	(a) T₁ = 0.693/λ	(b) T ₁= 1.43 λ	(c) T₁ = 0.693 λ	(d) None
14)	The number of protons in an atom are always equal to number of
	(a) Electrons	(b) Neutrons	(c) Positrons	(d) mesons
15)	Which of the following has no charge?
	(a) Alpha particle	(b) Beta particle	(c) Gamma Particle	(d) None
16)	When a nucleus emits alpha particle, its mass number drops to
	(a) 1	(b) 2	(c) 4	(d) 6
17)	Radioactivity happens due to disintegration of
	(a) Nucleus	(b) Mass	(c) Electron	(d) Protons
18)	The charge on beta particle is
	(a) +e	(b) –e	(c) +2e	(d) None
19)	Which one belong Leptons group?
	(a) Electron	(b) Muons	(c) Neutrinos	(d) All
20)	Mass of mesons is
	(a) Greater than proton	(b) Less than proton	(c) Equal to proton	(d) Equal to neutron
21)	The average of the background radiations to which we are exposed
	(a) 2 mSv	(b) 1 mSv	(c) 3 mSv	(d) 0.01 mSv
22) Two down and one up quarks make

	(a) Proton	(b) Neutron	(c) Photon	(d) Positron
23)	Which particle has larger range in air
	(a) Alpha particle	(b) Beta particle	(c) Gamma Particle	(d) Neutron
24)	The number of isotopes of cesium are
	(a) 4	(b) 32	(c) 36	(d) 22
25)	Binding energy of deuteron nucleus is given by
	(a) 2.8 Mev	(b) 2.23 Mev	(c) 2.28 Mev	(d) 2.25 Mev

Q-2. Write short answers of the following questions.

1) What are isotopes? Write some uses of isotopes.

2) What is mass defect and binding energy?

3) What are the main parts of Nuclear Reactor?

4) What factors make a fusion reaction difficult to achieve?

5) Define half life of a radioactive element.

6) What fraction of a radioactive sample decays after two half lives?

7) Define atomic number and mass number?

8) A particle which produces more ionization is less penetrating. Why?

9) Write equation when α – particle emitted from radioactive element.

10) What is mass spectrograph? Write is construction and working.

11) The effects of human body depend upon the properties of the radiations. Explain why source emitting alpha particles inside the body is more dangerous than a source of same activity emitting gamma particles inside the body.

12) What do you understand by back ground radiations? State two sources of this radiation.

13) What do you mean by critical mass?

14) Why is heavy nucleus unstable?

15) What is fluorescence?

16) ¹³⁹Ba₅₆ emits beta particle and La is formed. What is reaction?

17) How cans radioactivity helps in the treatment of cancer?

18) State the advantages and disadvantages of fusion power from the point of view of safety pollution and

resources.

Q-3 (a). What is fission reaction? Explain how fission reaction is used in Nuclear Reactor.

(b). Calculate the energy ( in MeV) released in the following fusion reaction

1H² + 1H³ → 2He₄ + ₀n¹

Q- 4 (a) State and explain radioactivity

(b). A sheet of lead 5.0 mm thick reduces the intensity of a beam pf γ – rays by a factor 0.4.Find half value

thickness of lead sheet which will reduce the intensity to half of its initial value.

Q-5 (a) Write down the principle, construction and working of Geiger- Muller Counter

(b)A 75 kg person receives a whole body radiation dose of 24 mrad. Delivered by α – particles for which RBE

factor is 12. Calculate the absorbed energy in joules and equivalent dose in rem.?

National Academy of Modern Science Pattoki

NAMS Pattoki

Friday, 22 December 2017

Physics 2nd Year PAST PAPER CHAPTER WISE

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