© examsnet.com
Question : 28
Total: 37
SECTION - C
(a) Differentiate between electrical resistance and resistivity of a conductor.
(b) Two metallic rods, each of length
Solution:
(a)
(b) For resistor R 1
Resistivity = ρ 1
Length = L
Area = A 1
∴ R 1 = ρ 1 ×
For resistor R 2
Resistivity = ρ 2
Length = L
Area = A 2
∴ R 2 = ρ 2 ×
For the equivalent resistor
Resistivity = ρ
Length = L
Area = A = A 1 + A 2
∴ R = ρ ×
Since the resistors are connected parallel
Equivalent resistance= R =
Or,ρ ×
=
∴ ρ = =
| Electrical resistance | Resistivity |
|---|---|
| It is the property of material due to which it opposes the flow of electricity through the conductor | The resistivity is defined as the resistance of a material of 1 metre length and 1 square metre area of cross section. |
| Unit: Ohm | Unit: Ohm-Meter |
| Symbol: R | Symbol: |
| Length, cross-section area of conductor and temperature | Depends on temperature and material of the conductor |
For the equivalent resistor
Since the resistors are connected parallel
Equivalent resistance
Or,
© examsnet.com
Go to Question: