An iron-cored solenoid has self- inductance. 2.8 H. When the core is removed, the self inductance becomes 2 mH. What is the relative permeability of the core used?

Options

A. 1400
B. 1200
C. 2800
D. 2000

Answer

A

Explanation

`mu _(r) = L // L _(0) = 2. 8 xx (2 xx 10 ^(-3)) = 1400`