Electrostatics - Electromagnetism - Physics Previous Year Questions

Two point charges A = +3 nC and B = +1 nC are placed 5 cm apart in air. The work done to move charge B towards A by 1 cm is

An electric dipole has a pair of equal and opposite point charges \(q\) and \(-q\) separated by a distance \(2x\). The axis of the dipole is defined as

An electric dipole is placed in a uniform electric field with the dipole axis making an angle \(\theta\) with the direction of the electric field. The orientation of the dipole for stable equilibrium is

Consider a thin spherical shell of radius R consisting of uniform surface charge density s. The electric field at a point of distance x from its centre and outside the shell is

A charge of 0.8 C is divided into two charges Q\(_1\) and Q\(_2\). These are kept at a separation of 30 cm. The force on Q\(_1\) is maximum when

The potential energies associated with four orientations of an electric dipole in an electric field are

(i) \(-5U_0\) (ii) \(-7U_0\) (iii) \(3U_0\) (iv) \(5U_0\)

where \(U_0\) is positive. Rank the orientations according to the angle between the electric dipole moment p and electric field E, greatest first

Insulators can be charged by which of the following process?

Work done in moving a charge of 25C is 50 J. Calculate potential difference, between two points.

What is the electric field near infinite plane sheet of charge density \(\sigma\) ?

Which of the following diagram represents the variation of the electric field with distance r from the centre of a uniformly charged non-conducting sphere of radius R?

Charge on electron is

Two charged spheres of \(-20\mu\)C and \(60\mu\)C are kept at a certain distance. They are touched and kept again at the same distance. What is the ratio of force experienced before and after?

Two point charges \(20 \mu \mathrm{C}\) and \(-10 \mu \mathrm{C}\) are separated by a distance of \(1 \mathrm{~m}\) in air. At what point on the line joining the two charges, the electric potential is zero.

A spherical metal ball of density '\(\rho\)' and radius '\(r\)' is immersed in a liquid of density '\(\sigma\)'. When an electric field is applied in the upward direction the metal ball remains just suspended in the liquid. Then the expression for the charge on the metal ball is :

An electron and a proton having mass \(m_e\) and \(m_p\) respectively, initially at rest, move through the same distance '\(s\)' in a uniform electric field '\(E\)'. If the time taken by them to cover that distance is \(t_e\) and \(t_p\) respectively, then \(t_e / t_p\) is equal to:

The force between two electric point charges at rest in air is \(F_1\) When the same arrangement is kept inside water, the force between them is \(F_2\). Which of the following statement is correct?

PQRS is square of side \(1 \mathrm{~m}\). A charge of \(100 \mu \mathrm{C}\) is placed at the centre of the square. Then the work done to take \(3 \mu \mathrm{C}\) charge from the corner \(\mathrm{P}\) to the corner \(\mathrm{R}\).

Figure shows three arrangements of electric field lines. In each arrangement, a proton is released from rest at point \(\mathrm{P}\) and then accelerated through point \(\mathrm{Q}\) by the electric field. Points \(\mathrm{P}\) and \(\mathrm{Q}\) have equal separations in the three arrangements. If \(p_1 p_2\) and \(p_3\) are linear momentum of the proton at point \(\mathrm{Q}\) in the three arrangement respectively, then

A tiny ball of mass \(\mathrm{m}\) and charge \(\mathrm{q}\) is suspended from the fixed support using an insulating string of length \(1 \mathrm{~m}\). The horizontal uniform electric field \(\mathrm{E}\) is switched on. The angle made by the string with vertical when the ball is in equilibrium is \(45^{\circ}\). The magnitude of uniform electric field is

3 point charges each of \(-\mathrm{q}\) are placed on the circumference of a circle of diameter \(2 \mathrm{a}\) at \(\mathrm{A}, \mathrm{B}\) and \(\mathrm{C}\) respectively as shown in figure. The electric field at \(\mathrm{O}\) is