Question

Suppose we make for our Physics Laboratory a 10 micro-Henry inductor by wrapping a 0.030 cm diameter wire around a 4.0 mm diameter cylindrical core. How long must this core be?

Answer 1

Using the formula of self inductance

$L = \mu o π d² /4l$

$10^{-5} = ​​​​​​​4π ×10^{-7} × π (0.004)² /4l$

$l = 1.6 × 10^{-6} m$