WAEC Physics Past Questions & Answers - Page 148

736.

In which of the following media would sound wave travel fastest?

A.

wood

B.

water

C.

iron

D.

mercury

Correct answer is C

No explanation has been provided for this answer.

737.

A travelling microscope is focused on a mark on a table. If a glass block of thickness 18.0cm is placed on the mark, by how many centimeters will the microscope be moved upwards so as to focus the mark once again? [refractive index of glass = 1.5]

A.

27cm

B.

24cm

C.

9cm

D.

6cm

Correct answer is D

Apparent depth = \(\frac{\text{thickness}}{\text{refractive index}}\)

= \(\frac{18}{1.5} = 12cm\)

Upward adjustment = 18 - 12

= 6cm

738.

Which of the following distances is usually adjustable in the camera? The distance between the

A.

lens and the film

B.

diaphragm and the shutter

C.

shutter and the film

D.

diaphragm and the film

Correct answer is B

No explanation has been provided for this answer.

740.

The distance between the successive crests of a wave travelling at 20ms-1 is 25cm. Calculate the frequency of the wave

A.

0.8Hz

B.

5.0Hz

C.

50.0Hz

D.

80.0hz

Correct answer is D

f = \(\frac{v}{\pi} = \frac{20}{0.25} = 80Hz\)