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Physics questions and answers

Physics Questions and Answers

If you want to learn more about the nature and properties of matter and energy or you're simply preparing for a Physics exam, these Physics past questions and answers are ideal for you.

2,916.

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, 400001000 = 40kJ

2,917.

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.

2,919.

If a resistance is halved in value and the potential difference across it is tripled, then the ratio of the new current to the old one is

A.

1 : 6

B.

1 : 3

C.

2 : 1

D.

6 : 1

Correct answer is D

V1V2 = I1R1I2R2

I1I2V2 = 3V1 and R1 = 2R2

V13V1 = I1× 2R2I2×R2

I1I2 = 61

2,920.

At different locations on the earth's surface, the earth's magnetic field is

A.

the same in magnitude and direction

B.

the same in magnitude but different in direction

C.

different in both magnitude and direction

D.

different in magnitude but different in direction

Correct answer is A

No explanation has been provided for this answer.