JAMB Physics Past Questions & Answers - Page 235

1,171.

A narrow beam of white light can be split up into different colours by a glass prism. The correct explanation is that

A.

white light is an electromagnetic wave

B.

the prism has all the colours of the white light

C.

white light has undergone total internal reflection in the prism

D.

different colours of white light travel with different speeds in glass

E.

white ligth consist of yellow, green and red colours

Correct answer is D

No explanation has been provided for this answer.

1,172.

Two rays of light from a point below the surface of water are equally inclined to each other at 60o in water. What is the angle between the rays when they emerge into air? (Take the refractive index of water to be \(\frac{4}{3}\))

A.

41.8o

B.

44.1o

C.

60.0o

D.

83.6o

E.

120.0o

Correct answer is D

\(\frac{4}{3}\) = \(\frac{sin r_1}{sin 30}\) and \(\frac{4}{3}\) = \(\frac{sin r_2}{sin 30}\)

r1 = 41.8o and r2 = 41.8o

angle between them = r1 + r2

= 83.6o

1,173.

A convex mirror is used as a driving mirror because

i. its image is erect.
ii. it has a large field of view.
iii. it has a long focal length.

Identify the CORRECT statement(s)

A.

i and iii only

B.

i and ii only

C.

ii and iii only

D.

i, ii, and iii only

E.

i only

Correct answer is B

No explanation has been provided for this answer.

1,174.

A 45o triangular glass prism can be used as a reflector of light because

A.

A refraction never takes place in such a prism

B.

the angle of reflection equals the angle of incidence

C.

the refractive index of glass is less than 1

D.

it is transparent

E.

the critival angle angle for glass is less than 45o

Correct answer is E

No explanation has been provided for this answer.

1,175.

An object is placed 15cm in front of a concave mirror of radius 40cm. The image formed is

A.

virtual and 60cm behind the mirror

B.

real and 60cm behind the mirror

C.

virtual and at infinity

D.

real and at infinity

E.

virtual and 40cm from the mirror

Correct answer is A

u = f