WAEC Physics Past Questions & Answers - Page 187

931.

A converging lens of focal length 15cm forms a virtual image at a point 10cm from the lens. Calculate the distance of the object from the lens

A.

10.00cm

B.

6.00cm

C.

5.00cm

D.

1.50cm

Correct answer is B

\(\frac{1}{u} + \frac{1}{v} = \frac{1}{f} = \frac{1}{15} + \frac{1}{10}\)

u = 6.00

932.

The refractive index of a medium relative to air is 1.8. Calculate to the nearest degree, the critical angle for the medium

A.

68o

B.

56o

C.

34o

D.

18o

Correct answer is C

c = \(\sin^{-1} \frac{1}{n} = \sin^{-1} \frac{1}{1.8} = 34^o\)

933.

The size of the hole of a pin hole camera is increased. The resultant image formed becomes

A.

sharper

B.

reduced in size

C.

enlarged

D.

blurred

Correct answer is D

No explanation has been provided for this answer.

934.

In the wave equation y = Eo, sin(299t - \(\pi\)), Eo represents the

A.

amplitude

B.

frequency

C.

period

D.

wavelength

Correct answer is A

No explanation has been provided for this answer.

935.

A radio wave has a wavelength of 150m. If the velocity of radio waves in free spaces is 3 x 10\(^8\) ms\(^{-1}\), calculate the frequency of the radio wave

A.

4.50 x 1010Hz

B.

5.0 x 109Hz

C.

4.5 x 109Hz

D.

2.0 x 106Hz

Correct answer is D

f = \(\frac{V}{\lambda} = \frac{3 \times 10^8}{150}\)

= 2.0 x 10\(^6\) Hz