Question

When a certain length of wire is turned into one circular loop. tire magnetic induction at the centre of coil due to some current flowing is $B_1$, If the same wire is turned into three loops to make a circular coil. the magnetic induction at the center of this coil for the same current will be

• A. $B_1$
• B. ${9B}_1$
• C. ${3B}_1$
• D. ${27B}_1$

Answer 1

Answer: (B)

${9B}_1$

The magnetic field at the center of loop is given as:

$B=n^2{B}_0$

where $n$ is number of loops

here n = 3

So, $B=(3{)}^2{B}_1$

$=9B_1$