Note similarities to gravity: Electricity: (PE=0 at r=∞) V= 0 when r=∞

If V is the potential at some point, W=qV is the work needed to bring a charge, q,to that location from infinity. V is a scalar: V=V1+V2+… Suppose q1=3.5x10-8C and q2=-5.6x10-7C. Find the electric potential at a point 45cm from q1 and 68cm from q2.

New unit: 1eV=1 electron-volt 1eV is the work needed to move an elementary charge through ∆V=1V. A conductor is an equipotential surface. Because E ⊥ surface, no work is needed to move a charge, so ∆V=0.

Don’t forget! Uniform field: ∆V=-Ed HW: Read Sec 2-4 Do: 6-14