WAEC Physics Past Questions & Answers - Page 88

436.

Which of the following units is equivalent to the watt?

A.

kgms-2

B.

kgm2s-3

C.

kgm2s-2

D.

kgm2s-1

Correct answer is B

\(Power = \frac{\text{Work done}}{time}\)

= \(\frac{Force \times distance}{time}\)

= \(\frac{mass \times acceleration \times distance}{time}\)

= \(\frac{kg \times m \times m}{s^{2} \times s}\)

= \(kgm^{2} s^{-3}\)

437.

The rising of a liquid in an open and ended glass tube of narrow bore is

A.

osmosis

B.

adhesion

C.

capillarity

D.

surface tension

Correct answer is C

No explanation has been provided for this answer.

438.

Which of the following radiations emitted in radioactive decay has momentum, a fairly high penetrating power and is deflected by a magnet?

A.

alpha particles

B.

beta particle

C.

gamma radiation

D.

X-radiation

Correct answer is B

β Particles are equivalent to electrons but arise from radioactive decay of unstable atoms. They are emitted with a continuous range of energies up to a maximum that is characteristic of each radionuclide. Electrons have a greater range and penetrating power, but much less ionizing potential compared with α particles.

Beta particles are deflected by a magnetic field in an opposite direction to alpha particles confirming they must hold a charge opposite to alpha particles.

439.

Which of the following arrangements of radiations is in the order of decreasing penetrating power?

A.

\(\alpha, \beta, \gamma\)

B.

\(\alpha, \gamma, \beta\)

C.

\(\gamma, \beta, \alpha\)

D.

\(\beta, \gamma, \alpha\)

Correct answer is C

No explanation has been provided for this answer.

440.

Which of the following statements about X-rays is correct? X-rays

A.

are produced when a metal surface is irradiated with ultraviolet light

B.

are produced when a metal target is used to block fast moving electrons

C.

have long wavelengths and are therefore very penetrating

D.

are not part of the electromagnetic spectrum

Correct answer is B

No explanation has been provided for this answer.