Three capacitors of capacitances \(3~\mu\text{F}\), \(9~\mu\text{F}\) and \(18~\mu\text{F}\) are connected once in series and another time in parallel. The ratio of equivalent capacitance in the two cases \(\frac{C_s}{C_p}\) will be:
1. \(1:15\)
2. \(15:1\)
3. \(1:1\)
4. \(1:3\)
\(A,B\) and \(C\) are three points in a uniform electric field. The electric potential is:
1. | maximum at \(A\) |
2. | maximum at \(B\) |
3. | maximum at \(C\) |
4. | same at all the three points \(A,B\) and \(C\) |
Two charges \(q_1\) and \(q_2\) are placed \(30~\text{cm}\) apart, as shown in the figure. A third charge \(q_3\) is moved along the arc of a circle of radius \(40~\text{cm}\) from \(C\) to \(D.\) The change in the potential energy of the system is \(\dfrac{q_{3}}{4 \pi \varepsilon_{0}} k,\) where \(k\) is:
1. | \(8q_2\) | 2. | \(8q_1\) |
3 | \(6q_2\) | 4. | \(6q_1\) |
Three charges \(Q\), \(+q \) and \(+q \) are placed at the vertices of an equilateral triangle of side \(l\) as shown in the figure. If the net electrostatic energy of the system is zero, then \(Q\) is equal to:
1. | \(-\frac{q}{2} \) | 2. | \(-q\) |
3. | \(+q\) | 4. | \(\text{zero}\) |
1. | Electric potential at the surface of the cube is zero. |
2. | Electric potential within the cube is zero. |
3. | Electric field is normal to the surface of the cube. |
4. | Electric field varies within the cube. |
1. | \(V \neq 0 \text { and } \vec{E} \neq 0\) |
2. | \(V \neq 0 \text { and } \vec{E}=0\) |
3. | \(V=0 \text { and } \vec{E}=0\) |
4. | \(V=0 \text { and } \vec{E} \neq 0\) |
1. | \(9 \times 10^{-3}~\text{J}\) | 2. | \(9 \times 10^{-3}~\text{eV}\) |
3. | \(2~\text{eV/m}\) | 4. | zero |
In the figure the charge \(Q\) is at the centre of the circle. Work done by the conservative force is maximum when another charge is taken from point \(P\) to:
1. | \(K\) | 2. | \(L\) |
3. | \(M\) | 4. | \(N\) |
On rotating a point charge having a charge \(q\) around a charge \(Q\) in a circle of radius \(r\), the work done will be:
1. | \(q \times2 \pi r\) | 2. | \(q \times2 \pi Q \over r\) |
3. | zero | 4. | \(Q \over 2\varepsilon_0r\) |
Three uncharged capacitors of capacities \(C_1, C_2~\text{and}~C_3\) are connected to one another as shown in the figure.
If points A, B, and D, are at potential \(V_1, V_2 ~\text{and}~V_3\) then the potential at O will be:
1. | \(\frac{V_1C_1+V_2C_2+V_3C_3}{C_1+C_2+C_3}\) | 2. | \(\frac{V_1+V_2+V_3}{C_1+C_2+C_3}\) |
3. | \(\frac{V_1(V_2+V_3)}{C_1(C_2+C_3)}\) | 4. | \(\frac{V_1V_2V_3}{C_1C_2C_3}\) |