Question

The inductance of a long solenoid of length 1000 mm wound uniformly with 3000 turns on a cylindrical paper tube of 60 mm diameter is

• A. 3.2 $\mu$H
• B. 3.2 mH
• C. 32.0 mH
• D. 3.2 H

Answer 1

The correct option is C 32.0 mH

Ans : (c)
$L=\frac{{\mu }_0{N}^{2}A}{l}$
for $l=1000mm=1m$
$\therefore L=4\pi \times {10}^{-7}\times {3000}^2\times \pi \times (30\times {10}^{-3}{)}^2$
$=32mH$