Question

Magnetic field at point 'O' due to given current distribution. If 5 A current is flowing in this system and the diameter of the loop is 10cm.

• A. $2\times {10}^{-5}T,\otimes$
• B. ${10}^{-5}T,\odot$
• C. ${10}^{-5}T,\otimes$
• D. $2\times {10}^{-5}T,\odot$

Answer 1

The correct option is B ${10}^{-5}T,\odot$

Circular part will be equal and in opposite to each other. So, they will cancel each other.
So, magnetic field at 0 will be due to two straight wires only.
The magnetic field will be equal and in same direction due to each straight wire.
Field due to one straight wire $=B_1=\frac{\mu 0I}{4\pi R}$

$B_{Net}=2B_1=\frac{\mu 0I}{2\pi R}$

$B_{Net}=\frac{4\pi \times {10}^{-7}\times 5}{2\pi \times 0.1}=\frac{10\times {10}^{-7}\times 10}{0.1}$

$B_{Net}={10}^{-5}Tesla\odot outward$