Ch 17: Electric Potential Ch 17 introduces the idea of electric potential (also called Voltage)

Electric Potential Ch 17 looks at Electricity in terms of the ENERGY stored or available. Remember we looked at mechanics in terms of Forces and then Energy. Now we look at static electricity in terms of Forces (ch 16) and now Energy (ch 17).

Electric Potential Recall that change in Potential Energy = - Work done by a conservative force. We did this for gravitational PE. Now we look at this same idea in terms of electrical stored energy There is stored electrical energy because there is an electric force.

Electric Potential Recall E = F/q = electric Field So F = Eq W = Fd = Eqd = -change in U As charge moves through the electric field it loses electric potential energy U and gains Kinetic Energy. Energy is conserved, yes?!

Electric Potential Electric Potential is defined as the electric potential energy (U) per charge (q) Or V = U/q Voltage tells you how much energy there is per charge, measured in Joules per Coulomb.

Relation between Electric Potenial and Electric Field W/q = -U/q = Voltage W = -qV But W = Fd where F = Eq So W = Eqd = qV results in V = Ed V = Ed is the relationship between Voltage and Electric Field when the electric Field is uniform like between 2 parallel plates

17-4 The Electron Volt is a Unit of Energy When dealing with small amounts of charge, a Joule is a lot of energy. The Electron Volt is a unit of energy….it’s the energy required to move one electron thru a 1 Volt potential. 1 eV = qV =(1.6 x C)(1V)= 1.6 x J

17-5 Electric Potential Due to Point Charges Using the idea that the electric potential is zero at infinity, “it can be shown” that…. V = kQ/r This is the electric potential from a point source Q at some distance r.