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.

3,201.

A light wave travels from air into a medium of refractive index 1.54. If the wavelength of the light in air is \(5.9\times10^{-7}\)m, calculate its wavelength in the medium

A.

\(2.5\times10^{-7}\)m

B.

\(3.8\times10^{-7}\)m

C.

\(4.6\times10^{-7}\)m

D.

\(5.2\times10^{-7}\)m

E.

\(6.1\times10^{-7}\)m

Correct answer is B

n =\(\frac{wavelength\, in\, air}{wavelength\, in \,medium}= \frac{5.9\times10^{-7}}{1.54}= 3.8\times10^{-7}\)m

3,202.

Calculate the time taken to heat 2kg of water from 50°C to 100°C in an electric kettle taking 5A, from a 210V supply. (Specific heat capacity of water = 4200\(kg^{-1}K{-1}\)

A.

2.5 minutes

B.

5.7 minutes

C.

6.7 minutes

D.

7.5 minutes

E.

9.5 minutes

Correct answer is C

t = \(\frac{mc\theta}{p}= \frac{2\times4200\times50}{210\times5} \\ = 400s = 6.7\)

3,203.

The pressure of air in a tire is \(22.5Nm^{-2}\) at 27°C. If the air in the tyre heats up to 47°C, calculate the new pressure of the air, assuming that no air leaks out and that the change in volume of the air can be neglected.

A.

\(21.10Nm^{-2}\)

B.

\(24Nm^{-2}\)

C.

\(39.07Nm^{-2}\)

D.

\(45Nm^{-2}\)

E.

\(97.25Nm^{-2}\)

Correct answer is B

\(\frac{P_1}{T_1}=\frac{P_2}{T_2};P_2= \frac{22.5\times320K}{300K}=24Nm^{-2}\)

3,204.

\(500cm^{-3}\) of a gas is collected at 0°C and at a pressure of 72cm of mercury. What is the volume of the the gas at the same temperature and at a pressure of 76cm of the same mercury?

A.

\(\frac{76\times500}{72}cm^3\)

B.

\(\frac{72\times500}{76}cm^3\)

C.

\(\frac{72\times76}{500}cm^3\)

D.

\(\frac{76}{72\times500}cm^3\)

E.

\(\frac{72}{76\times500}cm^3\)

Correct answer is B

\(P_1V_1=P_2V_2, V_2= \frac{72\times500}{76}cm^3\)

3,205.

An electric kettle rated 1500W boils away 0.3kg of a liquid at its boiling point every 300s. Calculate the specific latent heat of the vaporisation of the liquid

A.

1.5 x \(10^6Jkg^-1\)

B.

1.35 x \(10^6Jkg^-1\)

C.

1.5 x \(10^5Jkg^-1\)

D.

4.5 x \(10^2Jkg^-1\)

E.

3 x \(10^2Jkg^-1\)

Correct answer is A

Pt=mI; I=\(\frac{1500\times300}{0.3}=1.5\times10^6Jkg^-1\)