Detailed Step-by-Step Solution
We are given:
Charge q₂ = +4 μC
Distance between charges = 30 cm
Since both charges are positive, the point where electric field becomes zero must lie between the two charges.
Step 1: Assume Position
Let the zero-field point be at a distance x from the +1 μC charge. Then distance from +4 μC charge = (30 − x).Step 2: Equate Electric Fields
Electric field due to a point charge:Step 3: Solve Equation
Frequently Asked Questions
Why is zero field point between the charges?
Because both charges are positive and their fields oppose each other between them.
Why is the point closer to +1 μC charge?
Because +4 μC produces stronger field, so the balance point must be nearer the smaller charge.
Can zero field exist outside the charges?
No. Outside the charges, fields act in same direction and cannot cancel.
What happens if one charge were negative?
The zero-field point would lie outside the two charges.
Does magnitude of charge affect position?
Yes. The zero-field point shifts toward the smaller charge.
Is electric potential also zero there?
Not necessarily. Electric field can be zero while potential is not zero.
Is this concept important for JEE?
Yes. Zero-field location is a very common electrostatics question.
What is the direction of fields between charges?
Each field points away from its respective positive charge.
Theory: Zero Electric Field Between Two Like Charges
Electric field due to a point charge is given by:
For two like charges:
• Outside the charges, fields act in same direction.
Therefore, zero electric field occurs only between two like charges.
The zero-field point lies closer to the smaller charge.