The magnetic field due to a current carrying circular loop of radius 3 cm at a point on its axis at a distance of 4 cm from the centre is 54 μT. The magnetic field (in μT) at the centre of the loop will be
Given x = 4 cm = 0.04 m and r = 3 cm = 0.03 m.
The magnetic field at a point on the axis of the loop is given by
B=μ0 I r22(r2+x2)32 (1)
Magnetic field at the centre of the coil is given by
Dividing (1) by (2), we get
Substituting the values of r and x, we get
B0B=12527 orB0=12527 B=12527×54 μ T=250 μ T
Hence the correct choice is (a).