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.

3,916.

The production and type of charge of a body can only be accounted for by the?

A.

deficiency or surplus of electrons

B.

equibrium in protons and neutrons

C.

deficiency or surplus of protrons

D.

deficiency or surplus of neutrons

Correct answer is A

No explanation has been provided for this answer.

3,917.

A cell of internal resistance r is connected to an external resistor R. The conductor for maximum power transfer is?

A.

R < r

B.

R = r

C.

R = 2r

D.

R > r

Correct answer is B

Power = I\(^2\)R 

= \((\frac{E}{R + r})^2 R\)

To get point of maximum power transfer, we take the derivative and equate it to 0.

\(P = E^2 (\frac{R}{(R + r)^2})\)

\(\frac{\mathrm d P}{\mathrm R} = E^2 (\frac{(R + r)^2 - 2R(R + r)}{(R + r)^4})\)

= \(E^2 (\frac{(R + r)[(R + r) - 2R}{(R + r)^4})\)

\(\frac{\mathrm d P}{\mathrm d R} = E^2 (\frac{r - R}{(R + r)^3})\)

Maximum power is gotten when r - R = 0 i.e. r = R.

 

3,918.

A drop of petrol makes a finger colder than a drop of water would because?

A.

petrol takes its latent heat of veporization from the finger

B.

petrol takes its latent heat of fusion from the finger

C.

water is more viscious than petrol

D.

water has higher surface tension dan petrol

Correct answer is A

No explanation has been provided for this answer.

3,919.

what is likely to happen if the glass of a thermometer expands more upon heating than the liquid inside?

A.

the glass will break

B.

the glass will shrink

C.

the liquid will rise up in the stem

D.

the liquid will go down in the stem

Correct answer is D

No explanation has been provided for this answer.

3,920.

The thermos flask is designed to?

A.

prevent heat loss or gain by conduction, convection amd radiation

B.

store hot tea or water

C.

prevent heat gain by conduction, convection and radiation

D.

prevent head lost conduction, convention and radiation

Correct answer is A

No explanation has been provided for this answer.