WAEC Past Questions and Answers - Page 3240

16,196.

A coil of inductance 0.12 H and resistance 4\(\Omega\), is connected across a 240V, 50Hz supply. Calculate the current through it. [\(\pi\) = 3.142]

A.

6.3A

B.

33.3A

C.

37.2A

D.

40.0A

Correct answer is A

XL = \(2\pi f L\)

= = 2 x 3.142 x 50 x 0.12

= 37.68\(\Omega\)

Z = \(\sqrt{R^2 + X_L^2} = \sqrt{4^2 + 37.68^2}\)

I = \(\frac{V}{z} = \frac{240}{37.89}\)

= 6.3A

16,197.

Which of the following devices does not makes use of eddy current for its action? A/An

A.

galvanometer

B.

speedometer

C.

induction furnace

D.

speedometer

Correct answer is A

No explanation has been provided for this answer.

16,198.

The capacitance of parallel plates capacitors varies

A.

inversely as the square of the distance between the plates

B.

directly as the square of the distance between the plates

C.

inversely as the distance between the plates

D.

directly as the distance between the plate

Correct answer is A

No explanation has been provided for this answer.

16,199.

Which of the following instruments is used to determine the accurate value of the electromotive force of a cell?

A.

voltmeter

B.

meterbridge

C.

voltameter

D.

potentiometer

Correct answer is D

No explanation has been provided for this answer.

16,200.

A potential difference of 12V is applied across the ends of a 6\(\Omega\) resistor for 10 minutes. Determine the quantity of heat generated

A.

720J

B.

1200J

C.

14400J

D.

43200J

Correct answer is C

Q = \(\frac{V^2 t}{R}

= \frac{12^2 \times 10 \times 60}{6}\)

= 14400J