WAEC Physics Past Questions & Answers - Page 176

876.

One difference between a reactance and a resistance in an alternating current circuit is

A.

resistance is larger than reactance

B.

energy is not diaaipated in a reactance

C.

energy is stored in a resistance but not in a reactance

D.

the current in a reactance is lower than in the resistance

Correct answer is D

No explanation has been provided for this answer.

877.

The maximum power dissipated by a 100\(\Omega\) resistor in a circuit is 4W. Calculate the voltage across the resistor

A.

10V

B.

20V

C.

25V

D.

400V

Correct answer is B

\(V^2 = PR = V = \sqrt{4} \times 100\)

= 20V

878.

A lamp is rated 240V 60W, calculate the resistance of its filament

A.

240\(\Omega\)

B.

360\(\Omega\)

C.

960\(\Omega\)

D.

1440\(\Omega\)

Correct answer is C

R = \(\frac{V^2}{P} = \frac{240^2}{60} = 960\Omega\)

879.
880.

Which of the following factors does not affect the the electric resistance of a wire?

A.

length

B.

mass

C.

temperature

D.

cross sectional area

Correct answer is B

No explanation has been provided for this answer.