JAMB Physics Past Questions & Answers - Page 311

1,551.

Which of the following is required to convert a milliammeter to an ammeter?

A.

A high resistance in parallel

B.

A high resistance in series

C.

A low resistance in parallel

D.

A low resistance in series

Correct answer is C

No explanation has been provided for this answer.

1,552.

If the maximum voltage across a 100ohms resistor is 20V, then the maximum power it can dissipate is

A.

5.00W

B.

4.00W

C.

2.00W

D.

25W

Correct answer is B

P = \(\frac{V^2}{R}\)

= \(\frac{20 \times 20}{100}\)

= 4W

1,553.

An electric current of 2 amperes flows in a heating coil of resistance 50 ohms for 3 minutes 20 seconds. Determine the heat produced

A.

0.5kJ

B.

8.0kJ

C.

20.0kJ

D.

40.0kJ

Correct answer is D

Heat energy = Elect. energy


heat energy= I2RT

= 2 X 2 X 50 X 200

= 40000J

to convert to kJ, divide J by 1000

hence, \(\frac{40000}{1000}\) = 40kJ

1,554.

The purpose of a dielectric material in a parallel plate capacitor is to

A.

increase its capacitance

B.

decrease its capacitance

C.

insulate the plate from each other

D.

increase the magnetic field between the plates

Correct answer is C

No explanation has been provided for this answer.