Magnetic Effects Of Current Question 12

Question 12 - 29 January - Shift 2

The electric current in a circular coil of four turns produces a magnetic induction $32 T$ at its centre.

The coil is unwound and is rewound into a circular coil of single turn, the magnetic induction at the centre of the coil by the same current will be :

(1) $8 T$

(2) $4 T$

(3) $2 T$

(4) $16 T$

Show Answer

Answer: (3)

Solution:

Formula: Magnetic field due to circular loop

$B=\frac{\mu_0 1}{2 R} \times 4$

$B^{\prime}=\frac{\mu_0 i}{2 R^{\prime}}$

$R^{\prime}=4 R$

$B^{\prime}=\frac{\mu_0 i}{8 R}$

$\frac{B^{\prime}}{B}=\frac{1}{16}$

$B^{\prime}=2 T$