Question

A closely wound solenoid 80 cm long has 5 layers of windings of 400 turns each. The diameter of the solenoid is 1.8 cm. If the current carried is 8.0 A, estimate the magnitude of B inside the solenoid near its centre.

Answer 1

l = 80 cm = 80 x 10^-2 m
p = 5
N = 400
n = $\frac{N}{l}$
= $\frac{400}{80\times {10}^{-2}}$
= 500
For one turn, B = μ₀nl
B = 4π x 10^-7 x 500 x 8
For p turns = pB
= 5 x 4π x 10^-7 x 500 x 8
= 8π x 10^-3