12th class (Fsc) Physics unit 8 MCQs
26. The change in wavelength of scattered photon in Compton effect is:
a. mo/hc(1 – cos θ)
b. h/moc(1 – cos θ)
c. h/moc2 (1 – cos θ)
d. h/moc2 (1 – cos θ)
27. A kg mass will be equivalent to energy:
a. 9×1016 J
b. 9×108 J
c. 9×1019 J
d. 9×1012 J
28. Photo electrons are emitted by using visible light when the metal is:
a. Nicked
b. Sodium
c. Cobalt
d. Copper
29. Disintegration of photon on striking a nucleus into an electron and positron is known as:
a. Pair production
b. Annihilation of matter
c. Photo electron effect
d. Compton effect
30. The special theory of relativity based on:
a. Three postulates
b. One postulate
c. Four postulates
d. Two postulates
31. Platinum wire becomes yellow at a temperature of:
a. 1600o C
b. 900o C
c. 500o C
d. 1300o C
32. The photon with energy greater then 1.02 MeV can interact with matter as:
a. HU pair production
b. Photoelectric effect
c. Annihilation of matter
d. Compton effect
33. For pair production, minimum energy of photon must be:
a. 931 MeV
b. 0.51 MeV
c. 2.10 MeV
d. 1.02 MeV
34. When platinum is heated it becomes orange at:
a. 1100o C
b. 500o C
c. 1300o C
d. 900o C
35. Compton’s shift for wavelength is maximum for scattering angle θ = .
a. 45o
b. 0o
c. 180o
d. 90o
36. In Compton effect the photon behaves as a:
a. Wave
b. Particle
c. Nucleon
d. Both A & B
37. Unit of Plank’s constant is same as that of:
a. Momentum
b. Acceleration
c. Entropy
d. Angular
38. Platinum wire becomes white at a temperature of:
a. 1100o C
b. 1600o C
c. 900o C
d. 1300o C
39. Compton’s effect is associated with:
a. X-rays
b. Gamma rays
c. Positive rays
d. Beta rays
40. At higher energies more than 1.02 Mev the dominant process is:
a. Pair production
b. Photo electric effect
c. Nuclear fission
d. Compton effect
41. Steefen-Boltzmann law is given by:
a. E= σT4
b. E= hf
c. λ x T =constant
d. E= mc2
42.Momentum of moving photon is given by:
a. hf
b. h/λ
c. hλ/c
d. hc/λ
43. Energy each position is given by:
a. 0.51 MeV
b. 2 MeV
c. 5 MeV
d. 1.02 MeV
44. For an electron, the rest mass energy is:
a. 0.611 MeV
b. 0.411 MeV
c. 0.711 MeV
d. 0.511 MeV
45. Energy of black body radiation depends upon:
a. Shape and size of body
b. Nature of surface of body
c. Temperature of the body
d. Nature of material of body
46. The rest mass energy of an electron positron pair is:
a. 1.2 MeV
b. 0.51 MeV
c. 1.00 MeV
d. 1.02 MeV
47. The minimum energy required by photon to create an electron-positron pair is:
a. 1.02 MeV
b. 0.52 MeV
c. 0.051 MeV
d. 1.51 MeV
48. When platinum wire is heated, it changes to cherry red at temperature:
a. 1100o C
b. 500o C
c. 1300o C
d. 900o C
49. The dimensions of plank’s constant is same as that of:
a. Acceleration
b. Energy
c. Angular momentum
d. Power
50. The rest mas of photon is:
a. 9.1×10-3 kg
b. Zero
c. 1.67×10-31 kg
d. 1.67×10-27 kg