- 1(current)
Q. No.Two identical charged conducting spheres \(A\) and \(B\) have their centres separated by a certain distance. Charge on each sphere is \(q\) and the force of repulsion between them is \(F. \) A third identical uncharged conducting sphere is brought in contact with sphere \(A\) first and then with \(B \) and finally removed from both. New force of repulsion between spheres \( A\) and \(B \) (Radii of \(A\) and \(B \) are negligible compared to the distance of separation so that for calculating force between them they can be considered as point charges) is best given as:
| 1. | \(\dfrac{F}{2}\) | 2. | \(\dfrac{3 F}{8}\) |
| 3. | \(\dfrac{3 F}{5}\) | 4. | \(\dfrac{2 F}{3}\) |
Subtopic: Â Coulomb's Law |
 63%
Level 2: 60%+
NEET - 2025
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The ratio of Coulomb's electrostatic force to the gravitational force between an electron and a proton separated by some distance is \(2.4\times 10^{39}.\) The ratio of the proportionality constant, \(k=\dfrac{1}{4\pi\varepsilon_0}\) to the gravitational constant \(G\) is nearly:
(Given that the charge of the proton and electron each \(=1.6\times 10^{-19},\) the mass of the electron \(=9.11\times 10^{-31}~\text{kg},\) the mass of the proton \(=1.67\times 10^{-27}~\text{kg}\) )
(Given that the charge of the proton and electron each \(=1.6\times 10^{-19},\) the mass of the electron \(=9.11\times 10^{-31}~\text{kg},\) the mass of the proton \(=1.67\times 10^{-27}~\text{kg}\) )
| 1. | \(10^{20}\) | 2. | \(10^{30}\) |
| 3. | \(10^{40}\) | 4. | \(10\) |
Subtopic: Â Coulomb's Law |
 62%
Level 2: 60%+
NEET - 2022
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A charge \(q\) is placed at the centre of the line joining two equal positive charges \(Q.\) The system of the three charges will be in equilibrium, if \(q\) is equal to:
| 1. | \(\dfrac{-Q}{4}\) | 2. | \(\dfrac{Q}{4}\) |
| 3. | \(\dfrac{-Q}{2}\) | 4. | \(\dfrac{Q}{2}\) |
Subtopic: Â Coulomb's Law |
 66%
Level 2: 60%+
NEET - 2013
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Two pith balls carrying equal charges are suspended from a common point by strings of equal length, the equilibrium separation between them is \(r\) (as shown in Fig. I). Now, as shown in Fig. II, the strings are rigidly clamped at half the height. The equilibrium separation between the balls now becomes:
| 1. | \(\dfrac{r}{\sqrt[3]{2}}\) | 2. | \(\dfrac{r}{\sqrt[2]{2}}\) |
| 3. | \(\dfrac{2r}{3}\) | 4. | none of the above |
Subtopic: Â Coulomb's Law |
 71%
Level 2: 60%+
AIPMT - 2013
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