The electric field near the surface of earth points downward and has a magnitude of 160 n/c (a) compare the upward electric force on an electron with the downward gravitational force 2.8e12 . the electric force is is much larger. o both forces are equal. o the gravitational force is is much larger x (upward force/ downward force) (b) what magnitude charge should be placed on a penny of mass 6 g so that the electric force balances the weight of the penny near earth's surface?

To understand the electric potential and electric field of a point charge in three dimensions consider a positive point charge q, located at the origin of three-dimensional space. throughout this problem, use k in place of 14? ? 0. part adue to symmetry, the electric field of a point charge at the origin must point from the origin.answer in one word.part bfind e(r), the magnitude of the electric field at distance r from the point charge q.express your answer in terms of r, k, and q. part cfind v(r), the electric potential at distance rfrom the point charge q.express your answer in terms of r, k, and q part dwhich of the following is the correct relationship between the magnitude of a radial electric field and its associated electric potential ? more than one answer may be correct for the particular case of a point charge at the origin, but you should choose the correct general relationship. a)e(r)=dv(r)drb)e(r)=v(r)rc)e(r)=? dv(r)drd)e(r)=? v(r)r