JAMB Physics Past Questions & Answers - Page 320

1,596.
1,597.

Three electric cells each of e.m.f 1.5V and internal resistance of 1.0\(\Omega\) are connected in parallel across an external resistance of \(\frac{2}{3}\)\(\Omega\). Calculate the value of the current in the resistor

A.

0.5 A

B.

0.9 A

C.

1.5 A

D.

4.5 A

Correct answer is C

E.m.f = 1.5

r = \(\frac{1 \times\ 1 \times 1}{(1 \times\ 1) + (1 \times\ 1) + (1 \times\ 1)}\)

r = \(\frac{1}{3}\)\(\Omega\)

I = \(\frac{E.m.f}{r + R}\)

I = \(\frac{1.5}{\frac{1}{3}\ + \frac{2}{3}}\)

I = 1.5A

1,598.

The electromagnetic waves that are sensitive to temperature changes are

A.

X-rays

B.

Gamma-rays

C.

Ultra-violet rays

D.

Infra-red rays

Correct answer is D

No explanation has been provided for this answer.

1,600.

A boy on looking into a mirror observed that his face appeared to have grown bigger. The boy must have been looking at a

A.

convex mirror with his face at the focus

B.

concave mirror with his face between the focus and the mirror

C.

concave mirror with his face at the focus

D.

convex mirror with his face between the focus and the mirror

Correct answer is B

No explanation has been provided for this answer.