Question

Point A is at a lower electric potential than point B. If a free electron is placed between A and B, it will:

• A. Move towards A
• B. Move towards B
• C. Move at right angles to the line AB
• D. Remain at rest

Hint:

Remember that a negative charge feels a force opposite to the direction of the electric field.

Answer 1

The Correct Option is B

Step 1: Find the field direction.
Electric field always points from higher potential to lower potential. Since B is at higher potential and A is at lower potential, the field between them points from B towards A.
Step 2: Find the force on a positive charge.
A positive test charge in this field would feel a force along the field direction, that is from B towards A.
Step 3: Flip it for the electron.
An electron carries negative charge, so the force on it is exactly opposite to the field direction, that is from A towards B.
Step 4: Conclude the motion.
Starting from rest and feeling a steady force from A towards B, the electron accelerates and moves towards B.
Final Answer: B) Move towards B.