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.

4,096.

The phenomenon that makes sound persist when its source has been removed is known as

A.

acoustic vibration

B.

rarefaction

C.

echo

D.

reverberation

Correct answer is D

No explanation has been provided for this answer.

4,097.

blowing air over a liquid aids evaporation by

A.

increasing its surface area

B.

decreasing its vapour pressure

C.

increasing its temperature

D.

decreasing its density

Correct answer is B

if you blow dry air over the glass you blow away this extra water vapor, thereby decreasing the amount of water vapor entering the glass. 

4,098.

a ray of light which strikes a glass slab from air at normal incidence passes through the slab

A.

undeviated and undisplaced at a lower speed

B.

deviated and undisplaced at a lower speed

C.

deviated and displaced at a lower speed

D.

undeviated and displaced at a faster speed

Correct answer is A

The angle of refraction will be zero as the angle of incidence is zero in this case. This is a rule, that whenever a ray strikes perpendicularly or normally to a surface, no refraction will take place and hence the ray will pass through without deviating from its path.

4,099.

water is a poor thermometric liquid because it

A.

is opaque

B.

is a poor conductor

C.

wets glass

D.

has low vapour pressure

Correct answer is B

No explanation has been provided for this answer.

4,100.

A concave mirror of radius of curvature 40 cm forms a real image twice as large as the object.
the object distance is

A.

10 cm

B.

30 cm

C.

40 cm

D.

60 cm

Correct answer is B

if r = 40 cm , then f = r/2 = 40/2 = 20 cm
then for a real image by a concave mirror,
magnification M = f/u-f => 2 = 20/U-20
therefore 2(u-20) = 20
2u - 40 = 20
2u = 40 + 20
2u = 60/2 = 30 cm