Two equal charges q are placed at a distance of 2a and a third charge –2q is placed at the midpoint. The potential energy of the system is -

1. $\frac{q^2}{8\pi {\epsilon }_{0}a}$

2. $\frac{6q^2}{8\pi {\epsilon }_{0}a}$

3. $-\frac{7q^2}{8\pi {\epsilon }_{0}a}$

4. $\frac{9q^2}{8\pi {\epsilon }_{0}a}$

Equipotential surfaces associated with an electric field which is increasing in magnitude along the x-direction are 

1. Planes parallel to yz-plane

2. Planes parallel to xy-plane

3. Planes parallel to xz-plane

4. Coaxial cylinders of increasing radii around the x-axis

What is the effective capacitance between A and B in the following figure 

1. 1 μF
2. 2 μF
3. 1.5 μF
4. 2.5 μF

In the figure, three capacitors each of capacitance 6 pF are connected in series. The total capacitance of the combination will be 

1. 9 × 10^–12 F

2. 6 × 10^–12 F

3. 3 × 10^–12 F

4. 2 × 10^–12 F

The charge on 4 μF capacitor in the given circuit is .... in μC 

1. 12

2. 24

3. 36

4. 32

A piece of cloud is having area \(25\times 10^{6}~\text{m}^2\) and an electric potential of \(10^5\) volts. If the height of cloud is \(0.75~\text{km}\), then find the energy of the electric field between the earth and the cloud will be: 
1. \(250~\text{J}\)
2. \(759~\text{J}\)
3. \(1225~\text{J}\)
4. \(1475~\text{J}\)

A parallel plate air capacitor has a capacitance of 100 μF. The plates are at a distance d apart. If a slab of thickness $t(t\le d)$ and dielectric constant 5 is introduced between the parallel plates, then the capacitance will be 

(1) 50 μμF

(2) 100 μμF

(3) 200 μμF

(4) 500 μμF

Five identical plates each of area A are joined as shown in the figure. The distance between the plates is d. The plates are connected to a potential difference of V volts. The charge on plates 1 and 4 will be 

(1) $\frac{{\epsilon }_{0}AV}{d}.\frac{2{\epsilon }_{0}AV}{d}$

(2) $\frac{{\epsilon }_{0}AV}{d}.\frac{2{\epsilon }_{0}AV}{d}$

(3) $\frac{{\epsilon }_{0}AV}{d}.\frac{-2{\epsilon }_{0}AV}{d}$

(4) $\frac{-{\epsilon }_{0}AV}{d}.\frac{-2{\epsilon }_{0}AV}{d}$

A network of four capacitors of capacity equal to $C_1=C,C_2=2C,C_3=3C$ and C₄ = 4 C are connected in a battery as shown in the figure. The ratio of the charges on C₂ and C₄ is 

(1) $\frac{22}{3}$

(2) $\frac{3}{22}$

(3) $\frac{7}{4}$

(4) $\frac{4}{7}$

The variation of potential with distance R from a fixed point is as shown below. The electric field at R = 5 m is 

(1) 2.5 volt/m

(2) –2.5 volt/m

(3) 2/5 volt/m

(4) –2/5 volt/m