WAEC Physics Past Questions & Answers - Page 119

591.

A cell of e.m.f. 1.5V is connected in series with a resistor of resistance 3.0\(\Omega\). A voltmeter connected across the cell registers 0.9V. Calculate the internal resistance of the cell

A.

2.0\(\Omega\).

B.

3.0\(\Omega\).

C.

5.0\(\Omega\).

D.

6.0\(\Omega\).

Correct answer is A

\(\frac{V}{R} = \frac{E}{R + r}\)

\(\frac{0.9}{3} = \frac{1.5}{3 + r}\)

r = 2\(\Omega\).

592.

A resistor of resistance R is connected to a battery of negligible internal resistance. If a siilar resistor is connected in series with it the

A.

effective resistance of the circuit is halved

B.

total power dissipated is doubled

C.

total current in the circuit is halved

D.

terminal voltage is halved

Correct answer is B

No explanation has been provided for this answer.

594.

When a conductor mounted on an insulating stand is charged and left for sometime, the conductor eventually loses all its charges. This is because the

A.

electric charges evaporate from the surface of the conductor

B.

charges are connected to earth

C.

charges on the conductor are neutralized by opposite charges from the surrounding air

D.

charges ionize the surrounding air

Correct answer is C

No explanation has been provided for this answer.

595.

A satellite in circular motion around the earth does not have

A.

a gravitational force acting on it

B.

a uniform velocity

C.

an acceleration

D.

a centripetal force acting on it

Correct answer is B

No explanation has been provided for this answer.