WAEC Physics Past Questions & Answers - Page 254

1,268.

The walls and ceilings of many standard auditoria are covered with perforated pads to

A.

increase the intensity of sound waves

B.

increase the loudness of sound waves

C.

reduce the effect of reverberations of sound waves

D.

increase the interference effect of sound waves

E.

decrease the frequency of sound waves

Correct answer is C

No explanation has been provided for this answer.

1,269.

Which of the following instruments produces sound by the vibration of air column?

A.

Piano

B.

Guitar

C.

Flute

D.

Hand bell

E.

Talking drum

Correct answer is C

No explanation has been provided for this answer.

1,270.

A converging lens of focal length 5cm forms a virtual image which is 10cm from the lens. How far from the lens is the object?

A.

2.0cm

B.

3.3cm

C.

5.0cm

D.

10.0cm

E.

15.0cm

Correct answer is B

\(f = \frac{uv}{u+v}\)

\(5 = \frac{-10u}{-10+u}\)

\(50 + 5u = -10u\)

\(50 = -10u - 5u\)

\(u = \frac{50}{-15}\)

u= -3.3cm