Question

$L$ is circular loop carrying a current. $P$ is a point on its axis $OX$. $dl$ is an element of length on the loop at a point $A$ on it. The magnetic field at $P$:

• A. due to $L$ is directed along $OX$
• B. due to $dl$ is directed along $OX$
• C. due to $dl$ is perpendicular to $OX$
• D. due to $dl$ is perpendicular to $AP$

Answer 1

Answer: (A), (D)

The correct options are
A due to $L$ is directed along $OX$
D due to $dl$ is perpendicular to $AP$

From figure, the magnetic field at $P$, due to $L$ is directed along $OX$ and due to $dl$ is directed along perpendicular to $AP$.

It is so because when whole loop will be considered, the vertical components due to $dl$ will get canceled out resulting into the effective components along horizontal direction.