(a) Aluminium
(b) Copper
(c) Silver
(d) Iron
Correct Answer: (c) Silver
Explanation
Silver has the lowest resistivity among all metals.
Notes for
More Information
CONCEPT: Electrical Resistivity
1. Electrical
resistivity, also called specific electrical resistance, is a property
of a material that indicates how strongly it opposes the flow of
electric current.
2. It is
denoted by the Greek letter ρ (rho).
3. The SI
unit of electrical resistivity is ohm-meter (Ω·m).
4. Resistivity
is an intrinsic property of a material and depends on:
·
Nature of the material
·
Temperature
Formula for Resistivity
5. Electrical
resistivity is given by:
Where:
= electrical resistance (Ω)
= length of the conductor
= cross-sectional area
Resistivity Values at Room
Temperature
6. Approximate
resistivity values of common metals are:
- Silver:
- Copper:
- Aluminium:
- Iron:
EXPLANATION
7. A lower
resistivity means less opposition to current flow.
8. Silver has
the lowest resistivity among all known metals.
9. Hence,
silver is the best conductor of electricity.
10.
Copper and aluminium also
have low resistivity, but their values are slightly higher than silver.
11.
Iron (and metals like tungsten)
have much higher resistivity, making them poor conductors compared
to silver and copper.
Final Answer
✅ Silver has
the lowest specific resistance.
Important Exam Points
12.
Low resistivity → good conductor
13.
High resistivity → poor conductor
14.
Silver is used in high-precision electrical contacts.
15.
Copper is commonly used in wiring due to good conductivity and
lower cost.
16.
Aluminium is used where light weight is required.
✔️ Key
One-Liner for Exams
Silver has the lowest
resistivity and is the best electrical conductor.