A non - conducting ring of mass m = 4 kg and radius R = 10 cm has charge Q = 2 C uniformly distributed over its circumference. The ring is placed on a rough horizontal surface such that the plane of the ring is parallel to the surface. A vertical magnetic field `B=4t^(3)T` is switched on at t = 0. At t = 5 s ring starts to rotate about the vertical axis through the centre. The coefficient of friction between the ring and the surface is found to be `(k)/(24)`. Then the value of k is

A non-conducting ring of mass m and radius R has a charge Q uniformly distributed over its circumference. The ring is placed on a rough horizontal surface such that plane of the ring is parallel to the surface. A vertical magnetic field B = B_0t^2 tesla is switched on. After 2 a from switching on the magnetic field the ring is just about to rotate about vertical axis through its centre. (a) Find friction coefficient mu between the ring and the surface. (b) If magnetic field is switched off after 4 s , then find the angle rotated by the ring before coming to stop after switching off the magnetic field.

A non-conducting ring of mass m and radius R has a charge Q uniformly distributed over its circumference. The ring is placed on a rough horizontal surface such that plane of the ring is parallel to the surface. A vertical magnetic field B = B_0t^2 tesla is switched on. After 2 a from switching on the magnetic field the ring is just about to rotate about vertical axis through its centre. (a) Find friction coefficient mu between the ring and the surface. (b) If magnetic field is switched off after 4 s , then find the angle rotated by the ring before coming to stop after switching off the magnetic field.

A non-conducting ring having q uniformly distributed over its circumference is placed on a rough horizontal surface. A vertical time varying magnetic field B = 4t^(2) is switched on at time t = 0. Mass of the ring is m and radius is R. The ring starts rotating after 2 s, the coefficient of friction between the ring and the table is

A non-conducting ring having q uniformly distributed over its circumference is placed on a rough horizontal surface. A vertical time varying magnetic field B = 4t^(2) is switched on at time t = 0. Mass of the ring is m and radius is R. The ring starts rotating after 2 s, the coefficient of friction between the ring and the table is

A non-conducting ring having q uniformly distributed over its circumference is placed on a rough horizontal surface. A vertical time varying magnetic field B = 4t^(2) is switched on at time t = 0. Mass of the ring is m and radius is R. The ring starts rotating after 2 s, the coefficient of friction between the ring and the table is

A conducting ring of radius 40 cm has a charge of 5 xx 10^(-9) C uniformly distributed over it. Calculate the electric field intensity at a point P, 40 cm away from the centre on the axis of the ring.

A charge q is uniformly distributed over a quarter circular ring of radius r . The magnitude of electric field strength at the centre of the ring will be