1. Give the SI unit of resistivity.

a) ohm/metre2

b) ohm metre2

c) ohm metre

d) ohm/metre

View Answer

Answer: c

Explanation: Resistivity = (Resistance×Area)Length

SI unit of resistivity=(ohm×metre2)metre

= ohm metre.

2. What is the reciprocal of resistivity of a material called? Give its unit.

a) Conductance, ohm-1

b) Conductivity, ohm-1 m-1

c) Conductance, ohm-1 m-1

d) Conductivity, ohm-1

View Answer

Answer: b

Explanation: Conductivity = 1Resistivity

SI unit of conductivity = 1ohmmeter

= ohm-1 m-1.

3. Give the SI unit of current density and its dimensional formula.

a) Am-2, [A1L-2]

b) Am2, [A1L2]

c) Am-1, [A1L-1]

d) Am1, [A1L1]

View Answer

Answer: a

Explanation: Current density is the amount of charge flowing per second through a unit area.

The SI unit of current density is ampere per square metre (Am-2) and its dimensions are [A1L-2].

4. Identify the factor which does not depend on the resistance of a conductor.

a) Nature of material

b) Area of cross-section

c) Length

d) Viscosity

View Answer

Answer: d

Explanation: The resistance of a conductor is directly proportional to its length, inversely proportional to the area of cross-section, and nature of the material. The resistance of the conductor does not depend on viscosity.

5. What is the reciprocal of resistance of a material called? Give its unit.

a) Conductance, ohm-1

b) Conductivity, ohm-1 m-1

c) Conductance, ohm-1 m-1

d) Conductivity, ohm-1

View Answer

Answer: a

Explanation: The conductance of a material is the ease with which electric charges flow through it.

Conductance=1Resistance.

SI unit of conductance=1ohm

=ohm-1.