Elementary Modern Physics - Jamb Physics Past Questions and Answers

Question 71:

• JAMB 2000

If the frequency of an emitted x-ray is 1.6 x 10¹⁶Hz, the accelerating potential is?
[e = 1.6 x 10^-19C, h = 6.63 x 10^-34Js]

A. 6630.0V
B. 663.0V
C. 66.3V
D. 6.6V

Question 72:

• JAMB 2000

If the fraction of the atoms of a radioactive material left after 120years is 1/64, what is the half-life of the material?

A. 24 years
B. 20 years
C. 10 years
D. 2 years

Question 73:

• JAMB 2000

A certain radioactive source emits radiations that were found to be deflected by both magnetic and electric fields. The radiations are

A. Beta rays
B. Gamma rays
C. X-rays
D. Unltr-violet rays

Question 74:

• JAMB 2000

Light of energy 5eV falls on a metal of work function 3eV and electrons are liberated. The stopping potential is

A. 1.7V
B. 2.0V
C. 8.0V
D. 15.0V

Question 75:

• JAMB 2001

The particles emitted when \( ^{39}_{19}K \text{ decay to } ^{39}_{19}K \) is

A. Gamma
B. Beta
C. Electron
D. Alpha