Class 12 NEET Physics Moving Charges and Magnetism

The magnetic field B produced at the centre of a circular coil due to current Iflowing through this is given by B=

µ0NI

2r

,N is number of turns and r is radius of the coil. Here B=

µ0I

2r

[N=1]∴ 2×2πr′=2πr( same length ).∴r′=

r

2

∴ Magnetic field at the centre for two turns (N=2) is given by
B′=

µ0×2I

2r′

=

µ0×2I

2r∕2

=

4µ0I

2r

=4B