Question

The coefficient of self inductance of a solenoid is 0.18 mH. If a crode of soft iron of relative permeability 900 is inserted, then the coefficient of self inductance will become nearly

• A. 5.4 Mh
• B. 162 Mh
• C. 0.006 mh
• D. 0.0002 Mh

Answer 1

Answer: (B)

162 Mh

Answer 2

We know for air cored solenoid $L = \frac { \mu _ { 0 } N ^ { 2 } A } { l }$

In case of soft of iron core it’s self inductance

$L ^ { \prime } = \mu _ { r } L$. So here L′ = 900 × 0.18 = 162 mH

Note : The self-inductance of a solenoid may be increased by inserting a soft iron core. The function of the core is to improve the flux linkage between the turns of the coil.