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.