Question

A metal wire of length 1cm and of uniform diameter has a resistance of 0.8 ohms. What is the resistance of a 50cm wire coil made of the same material but having twice its diameter?

​

Answer 1

Resistance is directly proportional to length, inversely proportional to cross-sectional area. Pay attention in class, and observe that even easy multiple choice questions can have only wrong answers if the setter makes a mistake.

Answer 2

20

Step-by-step explanation:

R= resistance P = resistivity

L = length A = area

0.8 = 1cm/A

R = J l/A => 0.8* 50*A/A

=> 0.8 * 25

=> 20