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JAMB Physics Past Questions & Answers - Page 188

936.

A landlord has eight 40W electric light bulbs, four 60W bulbs and two 100W bulb in his house. If he has all the points on for five hours daily and if N.E.P.A. charges 5k per unit, his bill for 30 days is

A.

N5.70

B.

N7.23

C.

N3.65

D.

N8.05

E.

N4.50

Correct answer is A

Total power = (8 x 40) + (4 x 60) + (2 x 100)

= 760W

Energy(Kwhr) = power x time

= 760 x 10-3 x 150

= 114kwhr.

If, 1kwhr. cost 5k

thus, 114 kwhr. will cost 5 x 114

= N5.70

937.

Which of the following statements is incorrect? The sensitivity of a galvanometer which incorporates an optical lever arrangement may be increased by providing

A.

a larger number of turns in the coil

B.

a thinner suspension with a small torsional control

C.

a special alloy permanent magnet which gives a high magnetic flux

D.

all of the above

E.

a light source with a greater intensity

Correct answer is D

No explanation has been provided for this answer.

938.

A man standing between two parallel mirrors in a barber's shop will see the following number of his own image

A.

eight

B.

two

C.

four

D.

one

E.

infinite

Correct answer is E

No explanation has been provided for this answer.

939.

If a given mass at constant pressure obeys the relation...volume is proportional to the absolute temperature...the gas is said to obey

A.

Hooke's Law

B.

Boyle's Law

C.

Dalton's Law

D.

Charles' Law

E.

Newton's Law

Correct answer is D

No explanation has been provided for this answer.

940.

An object is placed 30cm from a concave mirror of focal length 15cm. the linear magnification of the image produced is

A.

0

B.

23

C.

1

D.

2

E.

3

Correct answer is C

U = 30cm = 2f = r

V = 30cm

hence, m = vu = 3030

= 1