Federal Board 2017
PHYSICS
(Objective Type)
Inter (Part-2)
Allowed: 15 minutes
Note: Four possible answers A, B, C and D to each question are given. The choice which you think is correct that circle in front that question with Marker or Pen ink. 'Lining or filling two or more circles 'will result in zero mat k in that question. Write the letter A, B. C or D in the column. (Write correct "option) against each question also. If there k a contradiction in the bubble and hand written answer, bubble option will be considered correct.

• As mass number increases, which of the following does not change?

1. Density
2. Binding energy
3. Mass
4. Volume

• The half-life of radioactive element is:

1. T1 = 0.693 λ
2. T1 = λ/0.693
3. T_1/2 = 0.693/λ
4. T_1/2 = 1.43λ

• The direction of field lines due to a test charge " + q "is:

1. Circular
2. Curve
3. Radially outward
4. Radially inward

• The dimensional representation of Planck's constant is the same as:

1. Momentum
2. Angular momentum
3. Gravitational constant
4. Torque

• A capacitor of capacitance 'C' has a charge 'Q' and stored energy is ‘w’. If the charge is increased to '2Q.The stored energy will be:

1. 2w
2. 4w
3. w/4
4. w/2

• The amount of heat produced in a resistor when a current is passed through it, can be found by using:

1. Faradays law
2. Lenz's law
3. Joule's law
4. Kirchhoff’s rule

• The SI units of resistivity is:

1. Ωm
2. Ωm^-1
3. Ωm^-2
4. Ω^-1m^-1

• The e/m  of an electron moving with the speed along a circular path in a magnetic field is given as:

1. e/m = E²/B²R
2. e/m = ER/B²
3. e/m = B²R/E
4. e/m = E/B²R

• An instrument which can measure potential without drawing any current is:

1. Cathode Ray Oscilloscope (CRC)
2. Ammeter
3. Voltmeter
4. Galvanometer

• If L and R represent inductance and resistance respectively, then the dimensions of-will be:

1. [M⁰L^-1T^-2]
2. [M⁰L⁰T⁰]
3. [M⁰L⁰T^-1]
4. [M⁰L⁰T^-2]

• On what principle does a transformer work?

1. Ohm's Law
2. Mutual Induction
3. Electrostatic Induction
4. Electromagnetism

• "Eddy Currents" are set up in the direction:

1. At an angle 45' to the flux
2. Perpendicular to the flux
3. Parallel to the flux
4. Antiparallel to the flux

• The r.m.s value of the current when I0= 2,4 is given by:

1. 4√2A
2. (1/2√2) A
3. √2
4. 2√2

• If the capacitance of LC circuit is made four trnes then the frequency of the circuit becomes:

1. Four times
2. Thrice
3. Twice
4. One half

• What are substances called which undergo plastic deformation until they break?

1. Amorphous solids
2. Polymeric solids
3. Brittle substances
4. Ductile substances

• The substances in which magnetic fields produced by orbital and spin electrons of molecule add up to zero are called:

1. Paramagnetic
2. Super magnetic
3. Ferromagnetic
4. Diamagnetic

• In which type of logic gate, the output is one, when both inputs are zero?

1. NOT gate
2. NOR gate
3. CR gate
4. AND gat

SECTION-B
(Marks 42)

1. Electric lines of force never cross each other.
2. The potential is constant throughout a region of space. Is the electric field zero or non-zero in this region? Explain.
3. Is filament resistance lower or higher in a 500 W, 222 V light bulbs than in a 100 W, 220 V bulbs?
4. What are the difficulties in testing whether filament of a lighted but obeys Ohm's law?
5. What is meant by A.M. and F.M.?
6. Show graphically the phase relationship between current and voltage across an inductor.
7. Show that ε and Δφ/Δt  have the same units.
8. Does the induced emf always act to decrease the -magnetic flux through the circuit
9. What is meant by Hysteresis loss? How is it used in the construction of a transformer?
10. In a transformer, there is no transfer of charge from the primary to the secondary. How is then power transferred?
11. A sinusoidal current has rms value of 10 A. What is the maximum or peak value?
12. Which photon, red, green or blue carries the most energy and momentum?
13. If measurements show a precise position for an electron, can those measurements show precise momentum also? Explain.
14. Why a photodiode is operated in reversed biased state?
15. Write a short note on NAVSTAR navigation system?
16. How can the spectrum of hydrogen contain so many lines when hydrogen contains one electron?
17. If an electron and a proton have the same de-Broglie wavelength, which particle has greater speed?
18. What do we mean by the term critical mass?
19. Which radiation dose would deposit more energy to your body:
    (b)10 m Gy to your hand
    (b)1 m Gy dose to your entire body?

SECTION - C
(Marks 26)
Note: Attempt any TWO questions.

1. Derive an expression for energy stored in a charged capacitor. Also calculate the energy density stored in any electric field.
2. Explain how a moving coil galvanometer can be converted into:

   (i) An Ammeter
   (ii) A Voltmeter

3. What shunt resistance must be connected across a galvanometer of 50.0Ω resistance which gives full scale deflection with 2.0 mA current, so as to convert it into an ammeter of range 10.0 A?

Q4:

1. What are transistors? How can we use transistor as an amplifier?
2. What is voltage gain of an amplifier?
3. The current flowing into the base of a transistor is 100 μA. Find its collector current, I_C its emitter current I_E and the ratio I_C/I_E if the value of current gain β is 100.

Q5:

1. What is laser? Describe its principle and operation.
2. What is Compton Effect? How was the phenomenon explained by A.H. Compton on the basis of particle theory of light?
3. The half-life of 38Sr91 is 9.70 hours. Find its decay constant.