Physics
(Objective)
Time Allowed:-20 minutes
Marks:- 17
Note:-You haw four each objective type question as A, B, C and D. The choice which you think is correct, fill that circle in from of that question number. Use marker or pen to fill the circles. Cutting or filling two or more circles will result in zero mark in that question. Attempt as many question as given in objective type question paper and leave other blank. Use of link remover or white correcting fluid is not allowed.

• How many elections will have a charge of one coulomb?

(A) 6.2x10¹⁸
(B) 6.2x10¹⁹
(C) 5.2x10¹⁸
(D) 5.2x10¹⁹

• Two point’s charges +2coulomb and +6 coulomb repel each other if a charge of-2 coulomb is given to each of them then the electric force will be

(A) ON
(B) 8x10⁹N (attractive)
(C) 108x10⁹ N (repulsive)
(D) 12x10⁹(attractive and repulsive)

• The smallest resistance obtained by connecting 50 resistance each of Ω is

(A) 200 Ω
(B) Ω
(C) Ω
(D) Ω

• Ammeter is used to measure

(A) Resistance
(B) Voltage
(C) Current
(D) Capacitance

• Torque an a current carrying coil has the equation

(A) π =q(v x B)
(B) π = BILq
(C) π = BINA Cos α
(D) π = NLAB Cos α

• A rod of length 20 m is moving with 20m/s in a direction perpendicular to magnetic field of 20 T.What is the value of emf.

(A) 2000 V
(B) 4000 V
(C) 6000 V
(D) 8000 V

• A generator converts mechanical energy into

(A) Chemical energy
(B) Light energy
(C) Heat energy
(D) Electrical energy

• At resonance the value of current in ROC series circuit is equal to

(A) V_o/R
(B) V_oR
(C) 1/2
(D) Zero

• Which one is most energetic

(A) y- rays
(B) x- rays
(C) Ultra violet rays
(D) Visible light

• The critical temperature for mercury is

(A) 7.2 k
(B) 4.2 k
(C) 1.18 k
(D) 3.7 k

• The automatic working of streets lights is due to

(A) Inductor
(B) Capacitor
(C) Comparator
(D) Rectifier

• Gain of inverting op-amp in the R₁ = α and R₂₌0

(A) α
(B) 1
(C) 0
(D) -1

• The minimum energy needed for a photon to create an electron-positron pair is

(A) 1.02 Kev
(B) 0.51 Kev
(C) 0.51 Mev
(D) 1.02 Mev

• Davisson and Garner indicates_____in their experiment,

(A) Electron reflection
(B) Electron polarization
(C) Electron refraction
(D) Election diffraction

• Paschal series is obtained when all the 1121311ms of electron terminate on

(A) 2^nd orbit
(B) 3^rd orbit
(C) 4^th orbit
(D) 5^th orbit

• In Wilson cloud chamber we use

(A) Alcohol vapors
(B) Neon gas
(C) Bromine gas
(D) Water vapors

• A high potential Wave of____is used in G.M counter

(A) 400 volts
(B) 1000 volts
(C) 5000 volts
(D) 4000 volts

Physics (Subjective)
Time Allowed: 2:40 hours
Maximum Marks: 68

2. Answer briefly any eight parts from the followings: (8 x 2=16)

• How can you identify that which plate of a capacitor is positively charged?
• Suppose that you follow an electric field line due to a positive charge. Do electric field and potential increases or decreases.
• Verify that an ohm times Farad is equivalent to second.
• Prove that 1 =1
• What Lorentz force?
• What is right hand rule?
• How can you use a magnetic field to separate isotopes of chemical element?
• It is possible to orient a current loop in uniform magnetic field such that loop will not tend to rotate? Explain.
• Does the induced emf in a circuit depend on resistance of circuit? Does the induced current depend on resistance of the circuit?
• How can you position a flat loop of wire in a changing magnetic field so that there is no end induced in the loop?
• What is working principle of a transformer? Explain it.
• What is back emf effect in motors?

3. Answer briefly any Eight parts from the followings: - (8 x 2 =16)

• Stale Ohm's law and define resistance?
• What are the difficulties in testing whether the filament of a lighted bulb obeys Ohms law?
• Do bends in a wire affect its electrical resistance? Explain
• How does doubling the frequency affect the reactance of (a) an inductor (b) Capacitor?
• What is meant by A.M and F.M
• Define impedance and resonance frequency.
• Distinguish between intrinsic and extremis semi conductors.
• Define super conductor and critical temperature.
• What is meant by diamagnetic substances? Give examples.
• Why charge carriers are not present in the depletion region?
• Why a photo diode is operated in reverse biased state?
• Why ordinary silicon diodes do not emit light.

4. Answer briefly any six parts from the followings: 6 x 2 = 12

• As a solid is heated and begins to glow, why does it first appear red?
• What is an advantage an electron microscope has over an optical microscope?
• What is energy of a photon in joules, if its wavelength is 1240nm?(h=6.63x10³⁴Js,c=3x10⁸ms^-1)
• Is energy conserved when an atom emits a photon? Explain.
• What is population inversion?
• What are isotopes? Give two examples
• What happens to charge and mass of a radioactive nucleus when an a-particle is emitted from it?
• What do you understand by back ground radiation? State two sources of this radiation?
• How can radioactivity help in treatment of cancer? Explain briefly.

Section-II

Attempt any three questions. (8 x3 = 24)

5-(a) Write a note on resistivity and its dependence upon temperature,
(b) Two opposite point charges, each of magnitude q are separated by a distance2d. What is the electric potential at a point P midway between them?

6-(a) Explain how e/m (charge to mass ratio) for an electron is determined.
(b) An ideal step down transformer is connected to main supply of 240 volt. It is desired to operate a 12 volt, 30 watt lamp. Find the current in the primary and t transformation ratio.

7-(a) Describe the series resonance circuit amid calculate the frequency f we the properties of the series series resonance.
(b) What stress would cause a wire to increase the length by 0.01% if the Young's modulus of the wire is 12x10¹⁰Pa.What force would produce this stress if the diameter of the wiry is 0.56mm?

8-(a) Define depiction region. Barrier potential and transistor. Discuss current through npn transistor.
(b) An elector is placed in a box about the size of an atom that is about 1.0x10^-10. What is the velocity of the election?

9-(a) Describe the principle, construction and working of a Wilson Cloud Chamber?
(b) Calculate the longer wavelength radiation from the Paschen series