Question

Find the radius of wire of length 100m needed
to prepare a coil of resistance 25 ohm (Resitivity of
Material is 3.14×10^-7 ohm m)​

Answer 1

Answer:

r= 2×10^-7

Explanation:

Resistance= resistivity×length/area

25ohm = 3.14×10^-7×100/3.14×r^2

r^2 = 4 ×10^-7