Elementary Modern Physics - Jamb Physics Past Questions and Answers

Question 46:

• JAMB 1992

The threshold of frequency for photoelectric effect depends on the

A. Intensity of incident light
B. Frquency of incident light
C. Material of the photocathode
D. Potential difference between the cathode and the anode

Question 47:

• JAMB 1992

After three half lifes, the fraction of a radioactive material that has decayed is

A. \(\frac{1}{8}\)
B. \(\frac{1}{3}\)
C. \(\frac{2}{3}\)
D. \(\frac{7}{8}\)

Question 48:

• JAMB 1992

\(^{27}_{13}Al\) + \(^{1}_{0}n\) \(\Rightarrow\) \(^{24}_{11}Na\) + X

A. A proton
B. A gamma ray
C. A helium particle
D. An alpha particle

Question 49:

• JAMB 1993

Which of the following statements correctly describe(s) cathode rays? i. they consist of tiny particles carrying negative electric charges. ii. they are deflected in a magnetic field but not in an electric field. iii. they consist of fast moving neutrons and deflected in an electric field.

A. I only
B. Ii only
C. I and ii only
D. Ii and iii only

Question 50:

• JAMB 1993

Natural radioactivity is the random spontaneous disintegration of the nuclei of heavy isotopes of certain elements with the emission of

A. \(\alpha\), X, and \( \beta\)
B. \(\alpha\), \(\beta\) and \(\gamma\)-rays
C. X, \(\alpha\), \(\gamma\)-ray
D. \(\alpha\), \( \beta\) and X-rays