Waec Physics 1992 Past Questions and Answers

Question 56:

• WAEC 1992

An element whose half-life is 3 years has N atoms. How many atoms would have decayed after 9 years

A. 1 N atoms8
B. 1 N atoms3
C. 2 N atoms3
D. 5 N atoms6
E. 7 N atoms8

Question 57:

• WAEC 1992

When the nucleus of a uranium atom is split into two fragments of nearly equal mass the sum of the masses of the fragments is less than the mass of the original nucleus. This difference is a measure of the

A. Experimental error in calculating the separate masses
B. Change of momentum of each fragment
C. Potential energy lost
D. Nuclear energy released
E. Kinetic energy lost

Question 58:

• WAEC 1992

A sheet of paper is placed in the path of a beam of radiations from a radioactive source. Which of the following radiations will pass through the paper?I. Alpha rays II. Beta rays III. Gamma rays

A. I only
B. II only
C. III only
D. II and III only
E. I, II and III

Question 59:

• WAEC 1992

The process by which a metal, heated to high temperature, gives off electrons from its surface is known as

A. Photoelectric emission
B. Thermionic emission
C. Radioactive emission
D. Held emission
E. Secondary emission

Question 60:

• WAEC 1992

An electric string of length l is elastically stretched through a length e by a force F. The area of cross- section of the string is A and its Young’s modulus is E. Which of the following expressions is correct?

A. F = EA/eI
B. F = EAI/e
C. F = EAe/l
D. F = EAe