First slide

Magnetic field due to a current carrying circular ring

Question

Two concentric circular coils of ten turns each are situated in the same plane. Their radii are 20 cm and 40 cm and they carry 0.2 A and 0.3 A current, respectively, in opposite direction. The magnetic field in weber/m² at the centre is

Moderate

A

$\frac{35}{4} μ_{0}$
B

$\frac{μ_{0}}{80}$
C

$\frac{7}{80} μ_{0}$
D

$\frac{5}{4} μ_{0}$

Solution

Two coils carry current in opposite direction, hence net magnetic field at centre will be difference of the two fields.
$\begin{array}{l} i . e ., B_{net} = \frac{μ_{0}}{4 π} . 2 πN [\frac{i_{1}}{r_{1}} - \frac{i_{2}}{r_{2}}] \\ = \frac{10 μ_{0}}{2} [\frac{0 .2}{0 .2} - \frac{0 .3}{0 .4}] = \frac{5}{4} μ_{0} \end{array}$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App