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.

3,676.

If electron are accelerated from rest through a potential difference of 10kv, what is the wavelength of the associated electron
[m = 9.1 x 10-31kg, e = 1.6 x 10-19C, h = 6.6 x 10-34js]

A.

1.22 x 10-11m

B.

3.87 x 10-10m

C.

2.27 x 1011m

D.

2.27 x 1014m

Correct answer is A

λ = __h
√(2evm)

 

= ____6.6 x 10-34
√(2 x 1.6x10-19 x 10000 x 9.1x10-31)


1.223 x 10-11m

 

3,677.

Given the inductor of inductance 5mH, 10mH and 20mH connected in series, the effective inductance is

A.

0.35mH

B.

3.50mH

C.

2.90mH

D.

35.0mH

Correct answer is D

Left = L1 + L2 + L3
= 5mH + 10mH + 20mH = 35mH

3,678.

In the diagram above, the pressure of the gas is

A.

86 cm of mercury

B.

66 cm of mercury

C.

96 cm of mercury

D.

76 cm of mercury

Correct answer is A

Pressure of the Gas, P = A + h
= 76 + 10
86 cm Hg

3,679.

Find the effective resistance in the diagram above

A.

6 Ω

B.

12 Ω

C.

18 Ω

D.

24 Ω

Correct answer is D

∴ Reff = R1 + R2 + .....
= 4 + 4 + 4 + 4 + 4 + 4 = 24 Ω

3,680.

If a concave lens of focal length 12cm is used to produce a real image four times the size of the object, how far from the lens must the object be placed?

A.

10 cm

B.

15 cm

C.

20 cm

D.

25 cm

Correct answer is B

Magnifications = V/U = 4
∴ V = 4U
1/V + 1/U = 1/f
1/4u + 1/U = 1/12
5/4U = 1/12
4U = 12 x 5 = 60
∴ U = 15 cm