UNIVERSITY PHYSICS II CHAPTER 17 Electrical Potential Energy nd Electic pote s 17.1 Electrical potential energy and electric potential 1. Electric force is conservative force Coulomb’ s force:F= L Source charge: E Test charge: q OLF=qE araH=F.d=nEd≈9QF·d_gQdr W=l dn g @dr 92 1 4丌Enr24m。r1 1. Electric force is conservative force ) 1 1 ( 4 4 d d 4 d 4 ˆ d d d d 0 2 0 2 0 2 0 i f L r r r r qQ r qQ r W W r qQ r r qQr r W F r qE r f i = = = − = ⋅ = ⋅ = ⋅ = ∫ ∫ πε πε πε πε r r r r r Source charge： Test charge： q Q F qE r r = ' Q r r r a r b a r r r r b r r d q E r L dr + + §17.1 Electrical potential energy and electric potential Coulomb’s force: 2 21 0 21 ˆ 4 1 r r qQ F πε = r