JAMB Physics Past Questions & Answers - Page 291

1,451.

A concave mirror has a radius of curvature of 36cm. At what distance from the mirror should an object be placed to give a real image three times the size of the object?

A.

12cm

B.

24cm

C.

48cm

D.

108cm

Correct answer is B

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

v = 3u

18 = \(\frac{3u \times u}{3u + u}\)

u = 24cm

1,452.

When an object is placed very close to the pole of a concave mirror, the virtual image obtained is

A.

diminished and upright

B.

diminished and inverted

C.

enlarged and inverted

D.

enlarged and upright

Correct answer is D

No explanation has been provided for this answer.

1,454.

What is the frequency of the sound made by a siren having a disc with 32 holes and making 25 revolution per seconds?

A.

80Hz

B.

600Hz

C.

800Hz

D.

1600Hz

Correct answer is C

No of holes x Revolution

F = NH x NR

= 32 x 25

= 800Hz

1,455.

A note is the octave of another note if it has

A.

a frequency twice that of the first note

B.

frequency half that of the first note

C.

the same fundamental frequency as the first one

D.

a frequency frequency eight times that of the first note

Correct answer is A

No explanation has been provided for this answer.