Three concentric metal shells A, B and C of respective radii a, b and c (a < b < c) have surface charge densities +σ, -σ and +σ respectively. The potential of shell B is

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A charged oil drop is suspended in a uniform field of 3×10^{4} v/m so that it neither falls nor rises. The charge on the drop will be (Take the mass of the charge = 9.9×10^{-15} kg and g = 10 m/s^{2})

- 1.6 X 10
^{-18} - 3.2 X 10
^{-18} - 3.3 X 10
^{-18} - 4.8 X 10
^{-18}

A charge Q is placed at each of the opposite corners of a square. A charge q is placed at each of the other two corners. If the net electrical force on Q is zero, then Q/q equals

- -1
- 1
- -2√2
- -1/√2

If a charge q is placed at the centre of the line joining two equal charges Q such that the system is in equilibrium then the value of q is

- Q/4
- -Q/4
- Q/2
- -Q/2

On moving a charge of 20 coulombs by 2 cm, 2 J of work is done, then the potential difference between the points is

- 8 V
- 0.5 V
- 0.1 V
- 2 V

An electric dipole is placed along the x-axis at the origin P. A point P is at a distance of 20 cm from this origin such that OP makes an angle 60° with x axis. If electric field at P makes an angle θ with x-axis, the value of θ is?

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