The potential energy of particle in a force field is U = A / r^2 − B / r , where A and B are positive constants and r is the distance of particle from the centre of the field. For stable equilibrium, the distance of the particle is ?

Three charges, each +q, are placed at the corners of an isosceles triangle ABC of sides BC, AC and AB, D and E are the mid points of BC and CA. The work done in taking a charge Q from D to E is ?

Charges +q and −q are placed at points A and B respectively which are a distance 2L apart, C is the midpoint between A and B. The work done in moving a charge +Q along the semicircle CRD is ?

As per the diagram, a point charge +q is placed at the origin O. Work done in taking another point charge −Q from the point A[ coordinates (0, a)] to another point B [coordinates (a, 0)] along the straight path AB is ?

Two charges q1 and q2 are placed 30 cm apart, as shown in the figure. A third charge q3 is moved along the arc of a circle of radius 40 cm from C to D. The change in the potential energy of the system is q3/4πε0 k, where k is ?

An electric dipole has the magnitude of its charge as q and its dipole moment is p. It is placed in uniform electric field E. If its dipole moment is along the direction of the field, the force on it and its potential energy are respectively ?

A bullet of mass 2 g is having a charge of 2μC. Through what potential difference must it be accelerated, starting from rest, to acquire a speed of 10 m/s ?

Each corner of a cube of side l has a negative charge, −q. The electrostatic potential energy of a charge q at the centre of the cube is ?

A particle of mass m and charge q is placed at rest in a uniform electric field E and then released. The kinetic energy attained by the particle after moving a distance y is ?