Question

A coil is wound as a transformer of rectangular cross-section. If all the linear dimensions of the transformer are increased by a factor 2 and the number of turns per unit length of the coil remain the same, the self inductance increases by a factor of

• A. 16
• B. 12
• C. 8
• D. 4

Answer 1

The correct option is C 8

Self inductance $L={\mu }_0{N}^2\frac{A}{l}={\mu }_0{n}^{2}lA$

Where n is the number of turns per unit length and N is the total number of turns and

In the given question n is same. A is increased 4 times and l is increased 2 times and hence L will be increased 8 times.