A parallel plate air capacitor has a capacity of \(C\), the distance of separation between plates is \(d\) and potential difference \(V\) is applied between the plates. The force of attraction between the plates of the parallel plate air capacitor is:
1. \(\frac{C^{2} V^{2}}{2 d}\)
2. \(\frac{C V^{2}}{2 d}\)
3. \(\frac{C V^{2}}{d}\)
4. \(\frac{C^{2} V^{2}}{2 d^{2}}\)
1. | increases by a factor of \(4\). |
2. | decreases by a factor of \(2\). |
3. | remains the same. |
4. | increases by a factor of \(2\). |
In the given circuit if point \(C\) is connected to the earth and a potential of \(+2000~\text{V}\) is given to the point \(A\), the potential at \(B\) is:
1. | \(1500\) V | 2. | \(1000\) V |
3. | \(500\) V | 4. | \(400\) V |
The figure shows some of the equipotential surfaces. Magnitude and direction of the electric field is given by:
1. | \(200\) V/m, making an angle \(120^\circ\) with the \(x\text-\)axis |
2. | \(100\) V/m, pointing towards the negative \(x\text-\)axis |
3. | \(200\) V/m, making an angle \(60^\circ\) with the \(x\text-\)axis |
4. | \(100\) V/m, making an angle \(30^\circ\) with the \(x\text-\)axis |
When a negative charge is released and moves in the electric field, it moves towards a position of:
1. | lower electric potential and lower potential energy. |
2. | lower electric potential and higher potential energy. |
3. | higher electric potential and lower potential energy. |
4. | higher electric potential and higher potential energy. |
In the given figure if \(V = 4~\text{volt}\) each plate of the capacitor has a surface area of\(10^{-2}~\text{m}^2\) and the plates are \(0.1\times10^{-3}~\text{m}\)apart, then the number of excess electrons on the negative plate is:
1. | \(KC \over 2(K+1)\) | 2. | \(2KC \over K+1\) |
3. | \(5KC \over 4K+1\) | 4. | \(4KC \over 3K+1\) |
An air capacitor of capacity \(C= 10~\mu\text{F}\) is connected to a constant voltage battery of \(12\) V. Now the space between the plates is filled with a liquid of dielectric constant \(5\). The charge that flows now from battery to the capacitor is:
1. \(120~\mu\text{C}\)
2. \(699~\mu\text{C}\)
3. \(480~\mu\text{C}\)
4. \(24~\mu\text{C}\)
Four equal charges \(Q\) are placed at the four corners of a square of each side \(a\). Work done in removing a charge \(-Q\) from its centre to infinity is:
1. \(0\)
2. \(\frac{\sqrt{2} Q^{2}}{4 \pi \varepsilon_{0} a}\)
3. \(\frac{\sqrt{2} Q^{2}}{\pi \varepsilon_{0} a}\)
4. \(\frac{Q^{2}}{2 \pi \varepsilon_{0} a}\)
1. | \(V={p\cos \theta \over 4 \pi \varepsilon_0r^2}\) | 2. | \(V={p\cos \theta \over 4 \pi \varepsilon_0r}\) |
3. | \(V={p\sin \theta \over 4 \pi \varepsilon_0r}\) | 4. | \(V={p\cos \theta \over 2 \pi \varepsilon_0r^2}\) |