WAEC Physics Past Questions & Answers - Page 102

506.

An object is placed 20.0cm in front of a converging lens of focal length 15.0cm. Calculate its image distance

A.

1.3cm

B.

8.6cm

C.

35.0cm

D.

60.0cm

Correct answer is D

\(\frac{1}{v} = \frac{1}{f} - \frac{1}{U}\)

\(\frac{1}{15} - \frac{1}{20} = 60cm\)

507.

The speed of light in a certain medium is V while its speed in a vacuum is C. The absolute refractive index of the medium is

A.

C + V

B.

\(\frac{C}{V}\)

C.

\(\frac{V}{C}\)

D.

C - V

Correct answer is B

No explanation has been provided for this answer.

508.

Total internal reflection occurs in an optical prism when light rays

A.

travel from the prism into an optically denser medium

B.

are incident in the prism at an angle greater than the critical angle

C.

are incident normally in the prism

D.

travel from the prism to the air

Correct answer is B

No explanation has been provided for this answer.

509.

A ray undergoes a minimum deviation at 40o when it is incident on equilateral triangular glass prism. Calculate the refractive index of the prism

A.

1.48

B.

1.50

C.

1.53

D.

1.67

Correct answer is C

n = \(\frac{\sin \frac{1}{2} (dm + A)}{\sin \frac{1}{2} A}\)

= \(\frac{\sin \frac{1}{2} (40 + 60)}{\sin \frac{1}{2} \times 60}\)

= 1.532

510.

The image formed by a convex mirror is always

A.

real, erect and diminished

B.

real, inverted and diminished

C.

virtual, inverted and diminished

D.

virtual, erect and diminished

Correct answer is D

No explanation has been provided for this answer.