Question

The electric charge, in uniform motion, produces:
A. Electric field only
B. Magnetic field only
C. Both ‘A’ and ‘B’
D. Neither ‘A’ nor ‘B’

Answer 1

Hint: Electric and magnetic fields are closely related. A changing electric field gives rise to a changing magnetic field and a changing magnetic field gives rise to a changing electric field.

Complete step by step answer:
An electric charge produces an electric field. This is similar in essence to the production of a gravitational field by a mass. The electric field (E) produced by an electric point charge at a distance r from it is given by
$\overrightarrow{E}=\dfrac{kq}{{{r}^{2}}}\widehat{r}$
Where q is the value of charge and k is the universal electric constant with value
$9\times {{10}^{9}}kg.{{m}^{3}}.{{s}^{-4}}.{{A}^{-2}}$
When an electric charge is in uniform motion, it gives rise to an electric current, as electric current is nothing but the ratio of charge flowing in a conductor to the time interval in which the charge flows.
Now, we know that a current carrying conductor produces a magnetic field. Therefore, since a moving electric charge produces a current and a current in turn produces a magnetic field, in essence a moving electric charge gives rise to a magnetic field also.
Thus, an electric charge in uniform motion produces both an electric field and a magnetic field.
Therefore, the correct option is C) Both ‘A’ and ‘B’.
Actually, electricity and magnetism are very closely related. A changing electric field gives rise to a changing magnetic field and a changing magnetic field gives rise to a changing electric field.

Note: Only moving electric charges produce both electric and magnetic fields. However, stationary electric charges produce only electric fields. This concept should be understood deeply.
The question should also be read by the student properly to determine whether the question describes a stationary electric charge or one in uniform motion. Else, a student can very easily make a silly mistake.