Atotal amount of positive charge q is spread onto a non-conducting flat circular annulus of inner radius a and outer radius b. the charge is distributed so that the charge density (charge per unit area) is given by sigma = c/r, where r is the distance from the center of the annulus to any point on it and c is a constant. (a) find the total charge q of the annulus. (b) find electric field of the annulus at any point p on the axis of the annulus and a distance x from the center of the annulus o. (c) calculate electric potential of the annulus at point p. (v at infinity is zero) (d) if a charge -q with mass m is released at point p, what will be its speed at the center of the annulus o? .