Waec Physics 1992 Past Questions and Answers

Question 21:

• WAEC 1992

A metal of mass 1.5 kg was heated from 27^oC to 47^oC in 4 minutes by a boiling ring of 75 W rating. Calculate the specific heat capacity of the metal, (Neglect heat losses to the surrounding)

A. 2.5 X10³J kg^-10C^-1
B. 6.0 X10²J kg^-10C^-1
C. 2.5 x 10²J kg^-10C^-1
D. 1.4 X10²J kg^-10C^-1
E. 1.0 x 10²J kg^-10C^-1

Question 22:

• WAEC 1992

A ray of light strikes a plane mirror at an angle of incidence i. Determine in terms of i the angle of deviation of the ray after reflection from the mirror.

A. I
B. 2i
C. 90^o-i
D. 90^o+ i
E. 180^o - 2i

Question 23:

• WAEC 1992

Images formed by a convex mirror are always

A. Inverted, real and diminished
B. Inverted, virtual and diminished
C. Erect, virtual and diminished
D. Erect, real and magnified
E. Erect, virtual and magnified

Question 24:

• WAEC 1992

Which of the following statements is not correct for a light ray passing through a rectangular glass block which is surrounded by air? It

A. Suffers a displacement at the point of emergence
B. Emerges parallel to the incident ray
C. Is partly reflected at the point of incidence
D. Is deviated at the point of emergence
E. Is reflected in the block

Question 25:

• WAEC 1992

In an experiment to measure1 the focal length f of a converging lens object distances u and corresponding image distance were measured and 1/u plotted against 1/v to obtain the graph illustrated. How would f be determined from this graph?

A. F= the slope of the graph
B. F= the intercept on the 1/u axis
C. F =the intercept on the 1/v axis
D. F = reciprocal of the slope
E. F = reciprocal of the intercept on either axes