Question 118: Electromagnetic Induction

Question

A copper wire is wound on a wooden frame, whose shape is that of an equilateral triangle. If the linear
dimension of each side of the frame is increased by a factor of 3, keeping the number of turns of the coil per
unit length of the frame the same, then the self inductance of the coil:

Accepted Answer

Total length L will remain constant
L = (3a) N        (N = total turns)
and length of winding = (d) N
(d = diameter of wire)
self inductance = $$\mu $$
0
n
2
A$$\ell $$
= $$\mu $$
0
n
2
$$\left( {{{\sqrt 3 {a^2}} \over 4}} \right)$$ dN
$$ \propto $$ a
2
N $$ \propto $$ a
So self inductance will become 3 times

Answer

decreases by a factor of $$9\sqrt 3 $$

Answer

increases by a factor of 27

Answer

decreases by a factor of 9

Answer

increases by a factor of  3

Electromagnetic Induction

A copper wire is wound on a wooden frame, whose shape is that of an equilateral triangle. If the linear dimension of each side of the frame is increased by a factor of 3, keeping the number of turns of the coil per unit length of the frame the same, then the self inductance of the coil:

Choose the correct answer: