JEE Main | 2018Magnetic field due to currentEasy

Question

The dipole moment of a circular loop carrying a current I, is m and the magnetic field at the centre of the loop is B1. When the dipole moment is doubled by keeping the current constant, the magnetic field at the centre of the loop is B2. The ratio B1B2 is :

Options

A.

3

B.

2

C.

12

D.

2

Solution

Dipole moment of circular loop is m
m1 = I.A = I.πR2 {R = radius of the loop}
B1 = μ0I2R
moment becomes double
⇒R becomes 2R (keeping current
constant)
m2 = I. π(2R)2 = 2.IπR2 = 2m1
B2 = =μ0I2(2R)=B12
B1B2=2

Create a free account to view solution

View Solution Free
Topic: Magnetic field due to current·Practice all Magnetic field due to current questions

More Magnetic field due to current Questions

In a region of space, a uniform magnetic field B exists in the y-direction. A proton is fired from the origin, with its ...A particle of specific charge (charge/mass) α starts moving from the origin under the action of an electric field =...Two concentric circular coils of 10 turns each are situated in the same plane. Their radii are 20 cm 40 and they carry c...In the figure, a charged sphere of mass m and charge q starts sliding from rest on a vertical fixed circular track of ra...Which one of the following line in integrals is correct ? Note : The direction of the loops orientation is shown in fig....