On a smooth horizontal table a disc is placed with non conducting ring with uniformly distributed charge q fixed on its circumference. Both disc and ring are of mass m and radius r. If a uniform magnetic field of induction B which is symmetric with centre of disc is switched on in vertically downward direction, find the angular speed attained by disc due to this.

Calculate potential on the axis of a disc of radius R due to a charge Q uniformly distributed on its surface.

Charge q is uniformly distributed on a disc of radius r. If the disc is rotated with a frequency v, then magnetic field induction at the centre will be

A non-conducting thin disc of radius R charged uniformly over one side with surface density sigma , rotates about its axis with an angular velocity omega . Find (a) the magnetic field induction at the centre of the disc (b) the magnetic moment of the disc.

A non-conducting disc having unifrom positive charge Q , is rotating about its axis with unifrom angular velocity omega .The magnetic field at the centre of the disc is.

A plastic disc of radius 'R' has a charge 'q' uniformly distributed over its surface. If the dis is rotated with a frequency 'f' about its axis, then the magnetic induction at the centre of the disc is given by

A uniform disc of mass M and radius R is hinged at its centre C. A force F is applied on the disc as shown. At this instant, the angular acceleration of the disc is

A circular disc of radius 20 cm is rotating with a constant angular speed of 2.0 rad//s in a uniform magnetic field of 0.2 T. Find the e.m.f. induced between the centre and rim of the disc. Given magnetic field is along the axis of rotation of disc.

A non-conducting thin disc of radius R charged uniformly over one side with surface density s rotates about its axis with an angular velocity omega . Find (a) the magnetic induction at the centre of the disc, (b) the magnetic moment of the disc.

A disc of mass m and radius R is free to rotate in a horizontal plane about a vertical smooth fixed axis passing through its centre. There is a smooth groove along the diameter of the disc and two small balls of mass m//2 each are placed in it on either side of the centre of the disc as shown in Fig. The disc is given an initial angular velocity omega_(0) and released. The angular speed of the disc when the balls reach the end of the disc is

A disc of mass 'm' and radius R is free to rotate in horizontal plane about a vetical smooth fixed axis passing through is centre. There is a smooth groove along the diameter of the disc and two small balls of mass m/2 each are placed in it on either side of the centre of the disc as shown in fig. The disc is given initial angular velocity omega_(0) and released. The angular speed of the disc when the balls reach the end of the disc is -