JEE PYQ: Electromagnetic Induction Question 23
Question 23 - 2019 (11 Jan Shift 1)
There are two long co-axial solenoids of same length $l$. The inner and outer coils have radii $r_1$ and $r_2$ and number of turns per unit length $n_1$ and $n_2$ respectively. The ratio of mutual inductance to the self-inductance of the inner-coil is:
(1) $\frac{n_1}{n_2}$
(2) $\frac{n_2}{n_1} \cdot \frac{r_1}{r_2}$
(3) $\frac{n_2}{n_1} \cdot \frac{r_2^2}{r_1^2}$
(4) $\frac{n_2}{n_1}$
Show Answer
Answer: (4)
Solution
Mutual inductance $M = \mu_0 n_1 n_2 \pi r_1^2 l$. Self inductance of inner coil $L = \mu_0 n_1^2 \pi r_1^2 l$. $\frac{M}{L} = \frac{n_2}{n_1}$.
BETA
