Question 686:

• JAMB 1992

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

Question 687:

• JAMB 1992

Which of the following properties make the convex mirror useful as a driving mirror? i. the image is real. ii. the image is erect. iii. it has a wide field of view. iv. the image is magnified.

A. I, ii, and iv
B. I, ii, iii
C. Ii and iii
D. I and iii

Question 688:

• JAMB 1992

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

Question 689:

• JAMB 1992

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

Question 690:

• JAMB 1992

Which of the following statements is CORRECT about a long-sighted boy who does not put on glasses?

A. He cannot see distant objects clearly
B. Rays of light from a close object are focused in front of his retina
C. His eye ball is too long
D. Parallel rays of light are focused behind his retina