WAEC Physics Past Questions & Answers - Page 307

1,531.

The image in a pine-hole camera is always

A.

diminished

B.

enlarged

C.

upright

D.

inverted

E.

blurred

Correct answer is D

No explanation has been provided for this answer.

1,532.

A ray of light is incidence on a plane mirror at an angle of 35o. What is the angle by the reflected ray with the surface of the mirror?

A.

125o

B.

70o

C.

65o

D.

55o

E.

35o

Correct answer is D

The angle of reflection is always equal to the the angle of incidence, which is the angle that the incoming ray, called incident ray makes with the normal.

(Please note that the angle of incidence and angle of reflection are always defined in terms of angle the ray makes with the normal. There is nothing like "angle of reflection with respect to mirror)

The angle of incidence can be calculated from the angle incident rays makes the reflection surface as:

Angle of incidence = 90 - Angle made with reflecting surface

The angle with the reflecting surface, that is mirror, is given as 35 degrees.

Therefore:

Angle of incidence = 90 - 35 = 55 degrees

And

Angle of reflection = angle of incidence = 55 degrees

1,533.

A short chain is usually attached to the back of a petrol tanker trailing behind it to ensure that the

A.

petrol tanker is balanced on the wheel

B.

heat generated by friction in the engine can be conducted to the floor

C.

charges generated by friction in the tanker can be conducted to the earth

D.

the tanker moves slowly as the chain touches the floor

E.

chain produces sound for the resonance of the tanker engine

Correct answer is C

No explanation has been provided for this answer.

1,534.

Which of the following instruments can be used to compare the relative magnitudes of charges on two given bodies?

A.

The electrophorous

B.

Ebonite rod

C.

Proof plane

D.

Gold leaf electroscope

E.

Capacitor

Correct answer is D

No explanation has been provided for this answer.

1,535.

All the heat generated by a current of 2A passing through a resistor of 6Ω for 2.5s is used to evaporate 5 g of a liquid at its boiling point. What is the specific latent heat of the liquid?

A.

60 Jg-1

B.

120 Jg-1

C.

300 Jg-1

D.

360 Jg-1

E.

1500 Jg-1

Correct answer is B

Electrical Energy = Heat Energy.
I2Rt = ml
22 x 6 25 = 5 x L.
L = 120 Jg-1.