JAMB Physics Past Questions & Answers - Page 274

1,366.

When light is incident on an object which is magenta in colour, which of the following colour would be absorbed?

A.

Red and blue

B.

Green only

C.

Red and green

D.

Red only

Correct answer is B

No explanation has been provided for this answer.

1,367.

For a short sighted person, light rays from a point on a very distant object is focused

A.

in front of the retina

B.

on the retina by a converging lens

C.

behind the retina by a diverging lens

D.

in front of the retina, a distance 2F from the lens

Correct answer is A

No explanation has been provided for this answer.

1,368.

What must be the distance between an object and a converging lens of focal length 20cm to produce an erect image two times the object height?

A.

20cm

B.

15cm

C.

10cm

D.

5cm

Correct answer is C

F = \(\frac{uv}{u + v}\); v = 2u

20 = \(\frac{ux - 2u}{u + (-2u)}\); u = 10cm

1,369.

A boy looks at the image of an object in a plane mirror. He observes two images, a main bright one and the other faint. The observed images result from?

A.

reflection only

B.

refraction only

C.

diffraction and interference

D.

reflection and refraction

E.

reflection and diffraction

Correct answer is A

No explanation has been provided for this answer.

1,370.

An object which is 3cm high is placed vertically 10cm in front of a concave mirror. If this object produces an image 40cm from the mirror, the height of the image is

A.

0.75cm

B.

4.00cm

C.

8.00cm

D.

12.00cm

Correct answer is D

\(\frac{\text {object height}}{\text{image height}}\) = \(\frac{\text {object distance}}{\text{image distance}}\)

\(\frac{3}{\text{image height}}\) = \(\frac{10}{40}\)

Image height = 12cm