(a) (i) What is meant by resistance of a conductor ? Define its SI unit. (ii) List two factors on which the…
(a) (i) What is meant by resistance of a conductor ? Define its SI unit.
(ii) List two factors on which the resistance of a rectangular conductor depends.
(iii) How will the resistance of a wire be affected if its
(1) length is doubled, and
(2) radius is also doubled ?
Give justification for your answer.
Solution
(a) (i) The property of conductor to resist the flow of charges through it.
If Potential difference across the two ends of a conductor is 1V and the current through it is 1A, then resistance 'R' of the conductor is 1Ω.
Alternate answer
1Ω = 1 volt / 1 ampere
(ii) Length of the conductor
Area of cross-section of the conductor
Nature of the material
Temperature (any two)
(iii) (1) The resistance will become one half of its original value.
R = ρ(l/A) = ρ(l/πr²)
R' = ρ.2L / π(2r)²
(2) R' = ρ.l/π(2r)² . 2/4 = R/2
Resistance will reduce to one half.