# One metallic sphere A is given a positive charge whereas another identical metallic sphere B of the exact same mass as of A is given an equal amount of negative charge. Then: (1) mass of A and mass of B are the same. (2) mass of A is more. (3) mass of B is less. (4) mass of B is more.

Subtopic:  Electric Charge |
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PMT - 2000
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The force between two charges 0.06 m apart is 5 N. If each charge is moved towards the other by 0.01 m, then the force between them will become:

 1 7.20 N 2 11.25 N 3 22.50 N 4 45.00 N
Subtopic:  Coulomb's Law |
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When $$10^{19}$$ electrons are removed from a neutral metal plate, the electric charge on it is?

 1 $$-1.6$$ C 2 $$+1.6$$ C 3 $$10^{19}$$ C 4 $$10^{-19}$$ C
Subtopic:  Electric Charge |
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Two charges each equal to 2μC are 0.5m apart. If both of them exist inside the vacuum, then the force between them is

(1) 1.89 N

(2) 2.44 N

(3) 0.144 N

(4) 3.144 N

Subtopic:  Coulomb's Law |
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PMT - 2001
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A solid conducting sphere of radius a has a net positive charge 2Q. A conducting spherical shell of inner radius b and outer radius c is concentric with the solid sphere and has a net charge –Q. The surface charge density on the inner and outer surfaces of the spherical shell will be?

(1)

(2)

(3)

(4) None of the above

Subtopic:  Gauss's Law |
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Three charges are placed at the vertices of an equilateral triangle of side ‘a’ as shown in the following figure. The force experienced by the charge placed at the vertex A in a direction normal to BC is

(1) ${Q}^{2}/\left(4\pi {\epsilon }_{0}{a}^{2}\right)$

(2) $-{Q}^{2}/\left(4\pi {\epsilon }_{0}{a}^{2}\right)$

(3) Zero

(4) ${Q}^{2}/\left(2\pi {\epsilon }_{0}{a}^{2}\right)$

Subtopic:  Coulomb's Law |
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AIIMS - 2003
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Two particles of equal mass $$m$$ and charge $$q$$ are placed at a distance of $$16~\text{cm}$$. They do not experience any net force. The value of $$\frac{q}{m}$$ is:
1. $$l$$
2. $$\sqrt{\frac{\pi \varepsilon_0}{G}}$$
3. $$\sqrt{\frac{G}{4\pi \varepsilon_0}}$$
4. $$\sqrt{4\pi \varepsilon_0 G}$$

Subtopic:  Coulomb's Law |
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An electron is moving around the nucleus of a hydrogen atom in a circular orbit of radius r. The Coulomb force $\stackrel{\to }{F}$ on electron is (Where $K=\frac{1}{4\pi {\epsilon }_{0}}$)

(1) $-K\frac{{e}^{2}}{{r}^{3}}\stackrel{^}{r}$

(2) $K\frac{{e}^{2}}{{r}^{3}}\stackrel{\to }{r}$

(3) $-K\frac{{e}^{2}}{{r}^{3}}\stackrel{\to }{r}$

(4) $K\frac{{e}^{2}}{{r}^{2}}\stackrel{^}{r}$

Subtopic:  Coulomb's Law |
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PMT - 2003
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Five balls numbered 1 to 5 are suspended using separate threads. Pairs (1, 2), (2, 4), and (4, 1) show electrostatic attraction, while pairs (2, 3) and (4, 5) show repulsion. Therefore ball 1 must be:

1. positively charged.

2. negatively charged.

3. neutral.

Subtopic:  Coulomb's Law |
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From NCERT
PMT - 2003
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Equal charges q are placed at the four corners A, B, C, D of a square of length a. The magnitude of the force on the charge at B will be

(1) $\frac{3{q}^{2}}{4\pi {\epsilon }_{0}{a}^{2}}$

(2) $\frac{4{q}^{2}}{4\pi {\epsilon }_{0}{a}^{2}}$

(3) $\left(\frac{1+2\sqrt{2}}{2}\right)\frac{{q}^{2}}{4\pi {\epsilon }_{0}{a}^{2}}$

(4) $\left(2+\frac{1}{\sqrt{2}}\right)\frac{{q}^{2}}{4\pi {\epsilon }_{0}{a}^{2}}$

Subtopic:  Coulomb's Law |
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From NCERT
PMT - 1994
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