JAMB Physics Past Questions & Answers - Page 114

566.

The image formed by a converging lens of focal length is of a distance of 2f from the lens. Calculate the lateral magnification produced

A.

0.5

B.

1

C.

1.5

D.

2

E.

3

Correct answer is B

Using the lens formula,

\(\frac{1}{v} + \frac{1}{u} = \frac{1}{f}\)

Where u, v and f are the object distance, image distance and focal length respectively.

\(\therefore \frac{1}{2f} + \frac{1}{u} = \frac{1}{f}\)

\(\frac{1}{u} = \frac{1}{2f} - \frac{1}{f} \implies \frac{1}{u} = \frac{1}{2f}\)

\(u = 2f\)

\(\therefore Magnification = \frac{\text{image distance}}{\text{object distance}}\)

= \(\frac{2f}{2f}\)

= 1

567.

An electric iron rated 250 V has a coil of resistance 125Ω. What is the cost of using it for I hour at 10k per kWh?

A.

1.25k

B.

2.50k

C.

5.00k

D.

10.00k

E.

20.00k

Correct answer is C

No explanation has been provided for this answer.

568.

To keep a lorry moving at a constant speed v, requires power p, from the engine. The force provided by the engine is

A.

\(\frac{1}{2}\)v

B.

pv

C.

\(\frac{p}{v}\)

D.

pv2

E.

\(\frac{p}{v^2}\)

Correct answer is C

No explanation has been provided for this answer.

569.

The unit of inductance is

A.

Weber

B.

Telsa

C.

Hertz

D.

Henry

E.

Farad

Correct answer is D

No explanation has been provided for this answer.

570.

A wave travels a distance of 20 cm in 3s. The distance between successive crests of the wave is 4cm. What is the frequency of the wave?

A.

0.60Hz

B.

1.67Hz

C.

7.50Hz

D.

15.00Hz

E.

26.67Hz

Correct answer is B

No explanation has been provided for this answer.