NTA Abhyas JEE Main2020PhysicsCurrent ElectricityPractice
A resistor is constructed as a hollow cylinder with inner and outer radii r a = 0.5 c m , r b = 1.0 c m respectively and resistivity ρ = 3.5 × 10 - 5 Ω m . The resistance of the configuration for the length of 5 cm cylinder is × 10 - 3 Ω .
Options
- A7.42
- B10.56
- C14.38
- D16.48
Correct answer
A. 7.42
Step-by-step solution
Given, l = 5 cm = 5 × 10 - 2 m ρ = 3.5 × 10 - 5 Ω m A = π 1 × 10 - 4 - 0.25 × 10 - 4 = 0.75 π × 10 - 4 m 2 = 7.5 π × 10 - 5 m 2 ∴ R = ρ l A = 3.5 × 10 - 5 × 5 × 10 - 2 7.5 π × 10 - 5 = 7.42 × 10 - 3 Ω