JEE Main · 2022 · 26 Jun 2022 · Shift 2 · Electromagnetic Induction

Two coils of self inductance

L_{1}

and

L_{2}

are connected in series combination having mutual inductance of the coils as M. The equivalent self inductance of the combination will be :

(A) $\frac{1}{L _{1}} + \frac{1}{L _{2}} + \frac{1}{M}$
(B) $L_{1} + L_{2} + M$
(C) $L_{1} + L_{2} + 2 M$
(D) $L_{1} + L_{2} - 2 M$ ✓ Correct

Answer: (D)

Solution

When two inductors are connected in series with mutual inductance M, the equivalent inductance depends on the relative direction of the currents. From the circuit diagram provided, the currents in both inductors flow in opposite directions through the mutual inductance region. Therefore, the mutual inductance subtracts:

L_{eq} = L_{1} + L_{2} - 2 M

JEE Main · 2022 · 26 Jun 2022 · Shift 2 · Single correct option

Practise more: all JEE Main PYQs on Electromagnetic Induction →

More JEE Main questions on Electromagnetic Induction

XPQY is a vertical smooth long loop having a total resistance R where PX is parallel to QY and separation between them is $l$ . A constant magnetic field B perpendicular to the plane of the loop exists in the entire space. A rod CD of length L ( $L > l$ ) and mass $m$ is made to sli …
JEE Main 2026View solution →
Three identical coils $C_{1}, C_{2}$ and $C_{3}$ are closely placed such that they share a common axis. $C_{2}$ is exactly midway. $C_{1}$ carries current $I$ in anti-clockwise direction while $C_{3}$ carries curre …
JEE Main 2026View solution →
Inductance of a coil with $1 0^{4}$ turns is 10 mH and it is connected to a dc source of 10 V with internal resistance of $10Ω$ . The energy density in the inductor when the current reaches $(\frac{1}{e})$ of its maximum value is …
JEE Main 2026View solution →
Figure shows the circuit that contains three resistances ( $9Ω$ each) and two inductors (4 mH each). The reading of ammeter at the moment switch $K$ is turned ON, is ______ A.
JEE Main 2026View solution →
A conducting circular loop is rotated about its diameter at a constant angular speed of $100 rad / s$ in a magnetic field of 0.5 T perpendicular to the axis of rotation. When the loop is rotated by $3 0^{\circ}$ from the horizontal position, the induced EMF is 15 …
JEE Main 2026View solution →
A capacitor C is first charged fully with potential difference of $V_{0}$ and disconnected from the battery. The charged capacitor is connected across an inductor having inductance L . In t s $25%$ of the initial energy in the capacitor is transferred to the induct …
JEE Main 2026View solution →