AIPMT 2011 Solved Papers
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Physics 2011
Q. 41. Light of two different frequencies whose photons have energies 1 eV and 2.5 eV respectively illuminate a metallic surface whose work function is 0.5 eV successively. Ratio of maximum speeds of emitted electrons will be
(1) 1: 5 (2) 1: 4
(3) 1: 2 (4) 1: 1
Sol :
Answer : (3)
Q. 42. In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by
(1) Decreasing the potential difference between the anode and filament
(2) Increasing the potential difference between the anode and filament
(3) Increasing the filament current
(4) Decreasing the filament current
Sol:
Fact
Answer : (2)
Q. 43. The half life of a radioactive isotope X is 50 years. It decays to another element Y which is stable. The two elements X and Y were found to be in the ratio of 1: 15 in a sample of a given rock. The age of the rock was estimated to be
(1) 100 years (2) 150 years
(3) 200 years (4) 250 years
Sol:
After t second fractional amount of X left is
,
t = 4 × T1/2
t = 4 × 50
= 200 years
Answer : (3)
Q. 44. Photoelectric emission occurs only when the incident light has more than a certain minimum
(1) Frequency (2) Power
(3) Wavelength (4) Intensity
Sol:
Concept of threshold frequency
Answer : (1)
Q. 45. Fusion reaction takes place at high temperature because
(1) Molecules break up at high temperature
(2) Nuclei break up at high temperature
(3) Atoms get ionised at high temperature
(4) Kinetic energy is high enough to overcome the coulomb repulsion between nuclei
Sol:
Fact
Answer : (4)