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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.

3,406.

How long does it take a 750 W heater operating at full rating to raise the temperature of 1 kg of water from 40oC to 70oC? (Take the specific heat capacity of water as 4200 J kg-1 K-1 and neglect heat losses).

A.

84s

B.

112s

C.

168s

D.

280s

E.

616s

Correct answer is C

Heat energy = Elect. energy

mcθ = power x time

1 x 4200 x (70 - 40) = 750 x t

t = 168s

3,407.

What amount of current would pass through a 10 Ω coil if it takes 21s for the coil to just melt a lump of ice of mass 10g at 0oC if there are no heat losses? (Latent heat of fusion of ice = 336 Jg1).

A.

16.00A

B.

4.00A

C.

0.50A

D.

0.25A

E.

0.06A

Correct answer is B

I2Rt = mI;

I = mIRt

= 10×33610×21

= 16

= 4.0A

3,408.

Electric motor primarily converts

A.

electrical energy into chemical energy

B.

electrical energy into heat energy

C.

kinetic energy into potential energy

D.

electrical energy into mechanical energy

E.

mechanical energy into light energy

Correct answer is D

No explanation has been provided for this answer.

3,410.

ln the diagram below, the galvanometer indicates a null-deflection. What is the potential difference between P and Q?

A.

0.0 V

B.

1.5 V

C.

2.0 V

D.

3.0V

E.

4.0 V

Correct answer is A

No explanation has been provided for this answer.