Q. A point charge is moving in clockwise direction in a circle with constant speed. Consider the magnetic field produced by the charge at a fixed point $P$ (not at the center of circle) on the axis of the circle. Then,
Moving Charges and Magnetism
Solution:
The point charge moves in circle as shown in figure. The magnetic field vectors at a point $P$ on the axis of circle are $\vec{B}_{A}$ and $\vec{B}_{C}$ at the instant the point charge is at $A$ and $C$, respectively, as shown in figure.
Hence, as the particle rotates in circle, only magnitude of magnetic field remains constant at $P$ but its direction changes.
