Question

A circular coil carrying a certain current produces a magnetic field B₀ at its centre. The coil is now rewound so as to have 3 turns and the same current is passed through it. The new magnetic field at the centre is-

• A.
• B. 9 B₀
• C. $\frac { \mathrm { B } _ { 0 } } { 3 }$
• D. 3 B₀

Answer 1

Answer: (B)

9 B₀

Answer 2

B = $\frac { \mu _ { 0 } \mathrm { Ni } } { 2 \left( \frac { \ell } { 2 \pi \mathrm {~N} } \right) }$

\ B µ N²