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.

3,996.

The particle and wave nature of matter are demonstrated in the equation

A.

λ = hc/E

B.

λ = h/P

C.

λ = c/f

D.

λ = 2 d sin θ

Correct answer is B

I wave - particle duality of matter, the momentum of sub-atomic particle is given by P = h/λ where h = planck constant ; λ = wave length
=> λ = h/P

3,997.

A moving coil galvanometer has a full-scale deflection of 3A equivalent to 30o deflection. The sensitivity of the instrument is

A.

33.0

B.

0.1

C.

90.0

D.

10.0

Correct answer is D

Sensitivity of a measuring instrument is given by deflection per unit current: and given that deflection = 30o; and current (I) = 3A: then the sensitivity of the meter = 30/0 = 10.0

3,998.

X rays can be used in the study of crystal structure because they

A.

have a very long-reaching wavelength

B.

have extremely short wavelength

C.

are invisible

D.

are very fast

Correct answer is B

No explanation has been provided for this answer.

3,999.

For semi conductor to have negative temperature coefficient of resistance implies that

A.

their resistance decrease with temperature

B.

The resistance increase with temperature

C.

their resistance is constantly changing with temperature

D.

they have electrons and holes at high temperature

Correct answer is A

Temperature coefficient of resistance is given by

α = Increase in resistance per oC rise in temp.
__resistance at 0oC

And for metals where resistance increase with temperature rise, temperature coefficient of resistance is positive; on the other hand in semi conductors, where resistance decrease with temperature rise, temperature coefficient of resistance is negative.

3,000.

An a.c circuit of e.m.f 12V has a resistor of resistance 8Ω connected in series to an inductor of inductive reactance 16Ω and a capacitor capacitive reactance 10Ω. The current flow in the circuit is

A.

1.4A

B.

1.2A

C.

12.0A

D.

14.0A

Correct answer is B

Current (I) in the circuit = V/Z
But z =
 R2 + (XL - XC)2 

=
 82 + (16 – 10) 2 

=
 64 + 36 

=
 100  = 10Ω

∴ Current (I) = V/Z = 12/10 = 1.2 A