WAEC Physics Past Questions & Answers - Page 155

771.

Light of energy 5.0 eV falls on a metal of work function 3.0 eV and electrons are emitted, determine the stopping potential. [electronic charge, e = 1.60 x 108ms-19]

A.

1.7V

B.

2.0V

C.

8.0V

D.

15.0V

Correct answer is B

\(V_8 \frac{hf - w_o}{e} = \frac{5.0 \times 1.60 \times 10^{-19} - 3.0 \times 1.6 \times 10^{-19}}{1.6 \times 10^{-19}} = 2.0V\)

772.

A process by which two light atoms join to form a new atom of higher atomic mass is

A.

natural radioactivity

B.

nuclear fission

C.

nuclear fusion

D.

chain reaction

Correct answer is C

No explanation has been provided for this answer.

773.

Beta particles are faster-moving

A.

protons

B.

electrons

C.

neutrons

D.

photons

Correct answer is B

No explanation has been provided for this answer.

774.

Which of the following statements is not a reason for using soft iron in making the core of a transformer? It

A.

retains its magnetism for a long time

B.

is easily magnitised

C.

reduces energy loss due to hysteresis

D.

is easily demagnetised

Correct answer is A

No explanation has been provided for this answer.

775.

Which of the following statements is an advantage of nuclear fusion over nuclear fission?

A.

The resulting chain reaction which produces large amount of energy

B.

no radioactve wave is produced as bye product

C.

very high temperature is required in the process

D.

the end product is lead

Correct answer is A

No explanation has been provided for this answer.