2nd Year Physics 3rd Quarter Book Paper

Q1. Multiple choice questions (Attempt all · 12 × 1 = 12)

1. The balloon model shows that as the balloon expands:
   1. Dots remain at the same distance
   2. Dots move closer
   3. Dots move farther apart
   4. Dots disappear
2. In a fission reaction, which particle is used to bombard U-235?
   1. Alpha particle
   2. Proton
   3. Neutron
   4. Positron
3. Increasing the intensity of incident light of constant frequency above the threshold frequency results in:
   1. Increase in photoelectric current
   2. Increase in kinetic energy of electrons
   3. Both a and b
   4. No change
4. Another important example of a standard candle is:
   1. Type 1A supernovae
   2. Pulsars
   3. White dwarfs
   4. Black dwarfs
5. If N is the number of undecayed nuclei, the activity is given by:
   1. A = λ/N
   2. A = N/λ
   3. A = λN
   4. A = N × T½
6. The energies of whole electrons in photoelectric effect
   1. change with intensity of light
   2. change with velocity of light falling on the metal surface
   3. change with frequency of light
   4. none of the above
7. Which law states that brightness of a source is inversely proportional to the square of its distance
   1. Law of brightness
   2. Direct Square Law of brightness
   3. Inverse Square Law of brightness
   4. Inverse Square Law of light
8. Velocity of alpha particles is approximately:
   1. Speed of light
   2. 0.05 – 0.1 c
   3. 0.5 – 0.9 c
   4. 0.001 c
9. The process of pair production takes place if the energy of photon is
   1. equal to 2mₒc²
   2. less than threshold
   3. greater than 2mₒc²
   4. none of these
10. Luminosity depends on
    1. Size of the star
    2. Temperature of the star
    3. Colour of the star
    4. Option 1 and 2
11. In alpha decay, the atomic number of nucleus:
    1. Increases by 2
    2. Decreases by 2
    3. Remains same
    4. Increases by 4
12. The minimum frequency of light required to emit electrons from a metal surface is called:
    1. Cut-off frequency
    2. Threshold frequency
    3. Critical frequency
    4. Surface frequency