JAMB Physics Past Questions & Answers - Page 280

1,396.

If a current carrying coil is mounted on a metal frame, the back e.m.f. induced in the coil causes

A.

inductance

B.

eddy currents

C.

elecro-magnetism

D.

dipole moment

Correct answer is B

No explanation has been provided for this answer.

1,397.

To convert an alternating current dynamo into a direct current dynamo, the

A.

number of turns in the coil is increased

B.

strength of the field magnet is increased

C.

slip rings are replaced with a split ring commutator

D.

coil is wound on a soft iron armature

Correct answer is C

No explanation has been provided for this answer.

1,398.

An equipment whose power is 1500W and resistance is 375 ohms would draw a current of

A.

0.10A

B.

2.00A

C.

4.00A

D.

77.5A

Correct answer is B

P = I2R \(\Rightarrow\) I = \(\sqrt\frac{P}{R}\)

I = \(\sqrt\frac{1500}{375}\)

= 2A

1,399.

Which of the following obeys Ohm's Law?

A.

Glass

B.

Diode

C.

All electrolytes

D.

All metals

Correct answer is D

No explanation has been provided for this answer.

1,400.

A moving coil galvanometer of 300\(\Omega\) resistance gives full scale deflection for 1.0mA. The resistance R, of the shunt that is required to convert the galvanometer into a 3.0A ammeter is

A.

899.70\(\Omega\)

B.

10.00\(\Omega\)

C.

0.10\(\Omega\)

D.

0.01\(\Omega\)

Correct answer is C

No explanation has been provided for this answer.