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.

4,086.

In the circuit above, the ammeter reads a current of 5.0 A when R = 8Ω and reads 7.0A when R = 5Ω. The value of the unknown resistance X is

A.

10.0Ω

B.

7.5Ω

C.

5.0Ω

D.

2.5Ω

Correct answer is D

From Ohms Law, E = I(R +X)
=> E = I1(R1 + X)
again, E = I2(R2 + X)
=> I1(R1 + X) = I2(R2 + X)
∴ 5(8 + X) = 7(5 + X)
40 + 5X = 35 + 7X
7X - 5X = 40 - 35
2X = 5
X = 5/2
= 2.5Ω

4,087.

The diagram above shows a magnet X with its south pole moved along a soft - iron bar PQ in the direction shown. After some time, the poles at P and Q respectively are

A.

North - North

B.

North - South

C.

South - North

D.

South - South

Correct answer is B

No explanation has been provided for this answer.

4,088.

The diagram above shows the prism arrangement in a

A.

binocular

B.

spectrometer

C.

periscope

D.

projector

Correct answer is C

No explanation has been provided for this answer.

4,089.

In the J-tube above, Y and X are on the same horizontal level and 30cm3 of air is trapped above Y when the atmospheric pressure is 75cm Hg, calculate the volume of air trapped above Y when 15cm Hg is now poured into the limb above X

A.

15 cm3

B.

25 cm3

C.

35 cm3

D.

45 cm3

Correct answer is B

Since the temperature of the air is to remain Constant => P1V1 = P2V2
∴ 75 x 30 = (75 + 15) x V2
75 x 30 = 90 x V2

=> V2 = 75 x 30
_90

 

= 2250
_90


= 25cm2

 

4,090.

The diagram above shows a lift pump with valves at P and Q. During a downward stroke of the piston

A.

both valves are open

B.

P is open while Q is closed

C.

P is closed while Q is open

D.

Both valves are closed

Correct answer is B

No explanation has been provided for this answer.