Four charges $$q,q$$ and $$-q,-q$$ are placed at the four vertices of a square of side $$a,$$ with like charges across a diagonal. The potential at the centre of the square is:
1. zero
2. $$\sqrt2\frac{kq}{a}$$
3. $$2\frac{kq}{a}$$
4. $$4\frac{kq}{a}$$
Subtopic:  Electric Potential |
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From NCERT
Hints

Two tiny spheres carrying charges of $$1.5$$ µC and $$2.5$$ µC are located $$30$$ cm apart. What is the potential at a point $$10$$ cm from the midpoint in a plane normal to the line and passing through the mid-point?
1. $$1.5\times 10^{5}$$ V
2. $$1.0\times 10^{5}$$ V
3. $$2.4\times 10^{5}$$ V
4. $$2.0\times 10^{5}$$ V

Subtopic:  Electric Potential |
From NCERT
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NEET 2025 - Target Batch
Hints
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NEET 2025 - Target Batch

A charge is uniformly distributed on the circumference of a disc, and the potential at its centre is $$5$$ volt. If the charge was uniformly distributed on the surface of this disc, the potential at a point $$P$$ on its axis, at a distance equal to the disc's radius from its centre, equals:
1. $$10$$ V
2. $$5 \sqrt 2$$ V
3. $$10 \sqrt 2$$ V
4. $$10 (\sqrt {2} -1)$$ V
Subtopic:  Electric Potential |
From NCERT
Hints
A negative point charge $$(-q)$$ is placed at the centre of a spherical ball of charge distributed uniformly over its volume. The radius of the ball is $$R.$$ The electric field on its surface is zero. The potential on its surface is:
2. $${kq \over 2R}$$
3. $${-kq \over 2R}$$
4. $${2kq \over R}$$