Physics Questions and Answers – Ohm’s Law

«
»

This set of Physics Multiple Choice Questions & Answers (MCQs) focuses on “Ohm’s Law”.

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 = \(\frac {(Resistance \, \times \, Area)}{Length}\)
SI unit of resistivity=\(\frac {(ohm \, \times \, metre^2)}{metre}\)
= ohm metre.
advertisement

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 = \(\frac {1}{Resistivity}\)
SI unit of conductivity = \(\frac {1}{ohm \, meter}\)
= 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].
Note: Join free Sanfoundry classes at Telegram or Youtube
advertisement
advertisement

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=\(\frac {1}{Resistance}\).
SI unit of conductance=\(\frac {1}{ohm}\)
=ohm-1.
advertisement

Sanfoundry Global Education & Learning Series – Physics – Class 12.

To practice all areas of Physics, here is complete set of 1000+ Multiple Choice Questions and Answers.

advertisement

advertisement
advertisement
Subscribe to our Newsletters (Subject-wise). Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Join our social networks below and stay updated with latest contests, videos, internships and jobs!

Youtube | Telegram | LinkedIn | Instagram | Facebook | Twitter | Pinterest
Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

Subscribe to his free Masterclasses at Youtube & technical discussions at Telegram SanfoundryClasses.