Physicshard · Past Paper
Two copper wires A and B have lengths in ratio 1:2 and radii in ratio 2:1. The ratio of their resistances is:
A1:2
B1:4
C1:8
D2:1
✓ Correct Answer: C — 1:8
R = ρL/(πr^2). R1/R2 = (L1/L2) * (r2/r1)^2 = (1/2) * (1/2)^2 = 1/2 * 1/4 = 1/8.
Share this question
More from Physics
- How much distance does a body cover in 5s if it starts from rest with acceleration 2 m/s^2?
- If the Earth stops rotating, the value of 'g' at the equator will:
- A body of mass 10 kg is moving on a horizontal frictionless surface with velocity 5 m/s. Work done by gravity is:
- How much heat is produced in a 5 Ohm resistor when 2 A current flows through it for 10 seconds?
- What is the magnification if the object height is 5 cm and the image height is 10 cm?