A small ball of mass `2 xx 10^-3` kg, having a charge 1 mu C, is suspended by a string of length 0.8 m. Another identical ball having the same charge is kept at the point of suspension. Determine the minimum horizontal velocity that should be imparted to the lower ball so that it can make a complete revolution.

A small stone of mass 200 g is tied to one end of a string of length 80 cm . Holding the other end in hand , the stone is whirled into a vertical circle What is the minimum speed that needs to be imparted at the lowest point of the circular path , so that the stone is just able to complete the vertical circle ? what would be the tension at the lowest point of circular path ? (Take g = 10 m//s^(2) ) .

A small cork ball with a mass 0.58 g is suspended from a thread 10 cm long. Another ball is fixed at a distance 10 cm from the point of suspension and at a distance of 5 cm from the thread as shown in the figure What shoud the magnitude of the like and equal charges on the balls be t deflect the thread through 30^@ ?

Two pith-balls each of mass 5xx10^-4 kg are suspended from the same point by silk threads 0.2 m long equal charges are given to the balls, which separate, until the threads enclose an angle of 30^@ , Calculate the charge on each pith-ball.

A ball of 0.03 m diameter and 0.3 kg in weight is attached to the end of a thin string of 0.46 m length. If it is rotate uniformly in a horizontal circle at the rate of 15 revolutions per second, what is the tension in the string? Take pi^2 = 9.87 ).

An ion of mass 2.8xx1O^(-26) kg carrying a charge 3.2xx10^(-19)C is revolving in circular path in a magnetic field of intensity 8xx 10^(-4) Tesla. Calculate the frequency of revolution.

A small particle carrying a negative charge of 1.6xx10^-19 C is suspended in equilibrium between the horizontal metal plates 5 cm apart, having a potential difference of 3000 volt across them. Find the mass of the particle.

Two small spheres each having mass m kg and charge q coulomb are suspended from a point by insultaing threads each l metre long but of negligible mass. If theta is the angle, each string makes with the vertical when equilibrium has been attained show that q^2 = (4m g l^2 sin ^2 theta tan theta) 4 pi upsilon_0

A point particle of mass M is attached to one end of a massless rigid non-conducting rod of length L. Another point particle of the same mass is attached to the other end of the rod. The two particles carry charges +q and -q respectively. This arrangement is held in a region of a uniform electric field E such that the rod makes a small angle theta (say of about 5 degree) with the field direction, fig. Find an expression for the minimum time needed for the rod to become parrallel to the field after it is set free.