# 1992 - JAMB Physics Past Questions and Answers - page 1

1

The angle between the direction of the earth's magnetic field and the horizontal is called the

A

angle of deviation

B

magnetic declination

C

magnetic meridian

D

angle of dip

**correct option:**d

2

Calculate the force acting on an electron of charge 1.6 x 10

^{-19}C placed in an electric field of intensity 10^{8}Vm^{-1}A

1.6 x 10

^{-11}NB

1.6 x 10

^{-14}NC

1.6 x 10

^{-16}ND

1.0 x 10

^{-16}N3

When an ebolite rod is rubbed with fur, it has

A

no charge at all

B

a negative charge

C

a positive charge

D

negative and positive charges

**correct option:**b

4

Which of the following factors has no effect on the e.m.f. of a primary cell?

A

temperature

B

size of the cell

C

nature of the plate

D

nature of the electrolyte

**correct option:**b

5

A wire of length 15m made of a material of resistivity 1.8 x 10

^{-6}\(\Omega\)m has a resistance of 0.27\(\Omega\). Determine the area of the wireA

1.5 x 10

^{-4}m^{2}B

1.0 x 10

^{-4}m^{2}C

2.7 x 10

^{-5}m^{2}D

7.3 x 10

^{-6}m^{2}**correct option:**b

Resistivity = \(\frac{\text {Resiatance x Area}}{length}\)

1.6 x 10

Area = 1.0 x 10

Users' Answers & Comments1.6 x 10

^{-6}= \(\frac{15 \times Area}{0.27}\)Area = 1.0 x 10

^{-4}m^{2}6

A 5-v battery is connected across the plates of a 2.0\(\mu\)F uncharged parallel plate capacitor. The charge on the capacitor after a long time is

A

2.5\(\mu\)C

B

10.0\(\mu\)C

C

20.0\(\mu\)C

D

50.0\(\mu\)C

7

Which of the following apparatus will require the smallest fuse rating for its protection?

A

60W, 240V

B

60W, 40V

C

40W, 12V

D

40W, 5V

**correct option:**a

I = \(\frac{P}{V}\) = \(\frac{60}{240}\) = 0.25A

I = \(\frac{P}{V}\) = \(\frac{60}{40}\) = 1.5A

I = \(\frac{P}{V}\) = \(\frac{40}{12}\) = 3.3A

I = \(\frac{P}{V}\) = \(\frac{40}{5}\) = 8A

Users' Answers & CommentsI = \(\frac{P}{V}\) = \(\frac{60}{40}\) = 1.5A

I = \(\frac{P}{V}\) = \(\frac{40}{12}\) = 3.3A

I = \(\frac{P}{V}\) = \(\frac{40}{5}\) = 8A

8

The heat produced in a conductor carrying an electric current is

A

inversely proportional to the current and the resistance

B

directly proportional to the current, resistance and the time

C

inversely proportional to of the resistance, current and the time

D

directly proportional to the square of the current, the resistance and the time

**correct option:**d

9

The maximum permissible current through a galvanometer G of internal resistance 10\(\Omega\) is 0.05A. A resistance R is used to convert G into a voltmeter with a maximum reading of 100V. Find the value of R and how it is connected to G

A

20,000 ohms in parallel

B

19,990 ohms in series

C

1990 ohms in series

D

100 ohms in series

**correct option:**c

10

In alternating current theory, the units of impedance, r.m.s. voltage and resonance frequency are respectively equal to

A

volt, ampere and hertz

B

ohms, volt and hertz

C

watt, ohms and radian

D

ohms, hertz and joule

**correct option:**b