Question

A negative charge is coming towards the observer. The direction of the magnetic field produced by it will be (as seen by observer)
A. Clockwise
B. Anticlockwise
C. In the direction of motion of charge
D. In the direction opposite to the motion of charge

Answer 1

Hint:In electromagnetism, a charged particle moving without acceleration produces electric as well as a magnetic field. It produces an electric field because of the nature of charge particles and when it starts moving it generates a magnetic field too.

Complete answer:
Let us first understand the nature of magnetic field lines produced by an electric charge. The force on a negative charge is in exactly the opposite direction to that of a positive charge.The direction of magnetic field lines due to a moving charge is always perpendicular to the plane formed by velocity direction and magnetic force.

Now, we can find the direction of magnetic field lines by pointing the right hand thumb in the direction of motion of a negatively charged particle, the curls of fingers give the direction of magnetic field lines. Since charge is moving towards the observer then pointing thumb in the direction towards the observer the fingers will curl in anticlockwise direction, this will happen for a positive charge but here it’s a negative charge so, for the observer, the direction of magnetic field line will be in clockwise direction.

Hence, the correct option is B.

Note:Remember, if a positive charge particle were moving towards the observer the direction of magnetic field lines would be in anticlockwise direction and also if this negative charge were going away from the observer then direction of magnetic field line would be anticlockwise.