Question

An observer at rest experiences an electric field due to a static charge. Later he starts moving away from it. Then the observer experiences

• A. Only magnetic field
• B. Only electric field
• C. Electric and magnetic field
• D. No field at all

Hint:

Electric and magnetic fields are frame-dependent quantities. A purely electric field in one inertial frame can appear as a combination of electric and magnetic fields in another frame moving relative to the first.

Answer 1

The Correct Option is C

Step 1: Static charge in rest frame.
A stationary observer sees only an electric field from a static charge.

Step 2: Apply special relativity — moving observer.
When the observer moves (or equivalently the charge moves relative to the observer), the moving electric field transforms to include a magnetic component. So the moving observer experiences both electric and magnetic fields.

\[ \boxed{\text{Both electric and magnetic fields}} \]