WAEC Physics Past Questions & Answers - Page 128

636.

A voltmeter is a device that

A.

draws high current

B.

has a very low resistance

C.

has a very high resistance

D.

is able to measure both voltage and current

Correct answer is D

No explanation has been provided for this answer.

637.

Three capacitors each of capacitance 1.5\(\mu F\) are connected in series. The total capacitance in the circuit is

A.

2.0 \(\mu F\)

B.

1.5 \(\mu F\)

C.

0.6 \(\mu F\)

D.

0.5 \(\mu F\)

Correct answer is D

No explanation has been provided for this answer.

638.

A wire 1.0m long and with cross-sectional area 2.0 x 10-7 m2 has a resistance of 0.1\(\Omega\). Calculate the electrical conductivity of the wire

A.

2.0 x 107\(\Omega^{-1} m^{-1}\)

B.

5.0 x 107\(\Omega^{-1} m^{-1}\)

C.

2.0 x 108\(\Omega^{-1} m^{-1}\)

D.

5.0 x 108\(\Omega^{-1} m^{-1}\)

Correct answer is B

K = \(\frac{1}{RA} = \frac{1}{0.1 \times 2 \times 10^{-7}} = 5 \times 10^7\)

639.

Which of the following is a unit of the time rate of flow of electric charges?

A.

coulomb

B.

ampere

C.

volt

D.

watt

Correct answer is B

No explanation has been provided for this answer.