JAMB Physics Past Questions & Answers - Page 178

886.

A potential difference of 6v is used to produce a current of 5A for 200s through a heating coil. The heat produced is

A.

4800 cal

B.

6000 cal

C.

2400J

D.

240k cal

E.

6000J

Correct answer is E

Heat energy = Elect. energy = Ivt

= 5 x 6 x 200

= 6,000J

887.

Why is it impossible for the lines of force of an electric field to cross one another?

A.

like charges repel each other

B.

a charged particle is deflected by an eletric field

C.

like charges are arranged on the same line of force

D.

a positively charged particle can travel in only one direction at any time

E.

none of these is correct

Correct answer is D

No explanation has been provided for this answer.

888.

On an a.c generator, which of the following does not apply?

A.

field magnet

B.

commutator

C.

armature

D.

slip rings

E.

carbon brushes

Correct answer is B

No explanation has been provided for this answer.

889.

In a D.C. circuit, a 10 microfarad (mf) capacitor is placed in series with a 10 ohm resistor. The total resistance of the combination is

A.

10 ohms

B.

1 ohms

C.

zero

D.

20 ohms

E.

infinite

Correct answer is E

Capacitor has an infinite resistance to D.C.

890.

In order to convert a galvanometer into an ammeter

A.

a low resistance shunt is connected in parallel

B.

a low resistance shunt is connected in series

C.

a medium resistance shunt is connected in series

D.

a high resistance shunt is connected in parallel

E.

a high resistance shunt is connected in series

Correct answer is A

No explanation has been provided for this answer.