A thin plastic rod of length 2.2 m is rubbed allover with wool, and acquires a charge of 53 nc, distributed uniformly over its surface. Calculate the magnitude thhe electric field due to the red at a location 15 cm from the midpoint of the rod. Do the calculation two ways, first using the exact formula for a rod of any length, and second using the apprnxirnate furmula fora long rad. (a) exact formula E = we (b) approximate formula E = NfC