In: Physics
Consider a charged disk of radius R on the x-z plane with its centre at the origin. The disk has a positive charge density σ. (a) Find, from first principles, an expression for the electric field of this disk at point P (0,yP,0) on the axis of the disk. (b) A second identical charged disk is now placed at a distance d parallel to the first, with its center at (0,d,0). Find the net electric field due to both disks at a point half way between the two disks at H (0,d/2,0). (c) A positive charge Q is now placed at H.
Use the results of part (b) to write an expression for the electric force acting on this charge. (d) What happens to charge Q if is displaced from H by a very small amount, y (y<<d/2), on the y-axis. Use Newton’s 2nd Law to discuss the motion of Q.