JAMB Physics Past Questions & Answers - Page 55

271.

Which of the following media allow the transmission of sound waves through them?
I. air
II. liquid
III. solids

 

A.

I & II only

B.

I & III only

C.

II & III only

D.

I, II & III

Correct answer is D

- sound travels through solids, liquids & gases
- sound travels faster in solid than in liquid & faster in liquid than in gases.

 

272.

The conductivity of gases at low pressure can be termed as
I. hot cathode emission
II. thermo ionic emission
III. cold cathode emission
IV. Field emission

A.

I & II

B.

II & III

C.

III & IV

D.

IV & V

Correct answer is C

As conduction of gases is at low pressure and high voltage, called field or cold cathode emission.

273.

In the molecular explanation of conduction, heat is transferred by the

A.

In the molecular explanation of conduction, heat is transferred by the

B.

Free atoms

C.

Free molecules

D.

Free solids

Correct answer is A

- Conduction is explained in terms of the free electrons.
- Convention is explained in terms of the movement of the fluid involved.
- Radiation is explained in terms of invisible electromagnetic wave

275.

During the transformation of matter from the solid to the liquid state, the heat supplied does not produce a temperature increase because

A.

the heat energy is quickly conducted away

B.

the heat capacity has become very large as the substance melts

C.

the heat gained is equal to the heat lost by the substance

D.

all the heat is used to break the bonds holding the molecules of the solid together

Correct answer is D

During the transformation of matter from the solid to the liquid state, the heat supplied does not produce a temperature increase because all the heat is used to break the bonds holding the molecules of the solid together