# Electric Potential AP Physics Chapter 17 Electric Charge

• Slides: 27

Electric Potential AP Physics Chapter 17

Electric Charge and Electric Field 17. 1 Electric Potential Energy and Potential Difference

Electric Potential Energy & Potential Difference Electricity can be viewed in terms of energy The electrostatic force is conservative because it depends on displacement Now We can calculate this value for a uniform electric field 17. 1

Electric Potential Energy & Potential Difference Positive test charge – increases when moved against the field Negative test charge – increases when moved with the field Electric Potential (Potential) – electric potential energy per unit charge 17. 1

Electric Potential Energy & Potential Difference Only difference in potential are meaningful Potential Difference (Electric Potential Difference) – is measureable Measured in volts (after Alessandro Volta) 17. 1

Electric Potential Energy & Potential Difference If we want a specific potential value at a point, we must pick a zero point. That point is usually either A. The ground B. At an infinite distance 17. 1

Electric Charge and Electric Field 17. 2 Relation between Electric Potential and Electric Field

Relation between Electric Potential & Electric Field Work It also is So pew 17. 2

Electric Charge and Electric Field 17. 3 Equipotential Lines

Equipotential Lines Equipotential Line or Equipotential Surface – one at which all points are at the same potential 17. 3

Equipotential Lines Must be perpendicular to the electric field Constant Field 17. 3

Equipotential Lines Must be perpendicular to the electric field Point Charge 17. 3

Equipotential Lines Must be perpendicular to the electric field Dipole 17. 3

Electric Charge and Electric Field 17. 4 The Electron Volt, a Unit of Energy

The Electron Volt A unit of energy – for electrons, atoms, or molecules Electron Volt (e. V) 17. 4

Electric Charge and Electric Field 17. 5 Electric Potential Due to Point Charge

Electric Potential Due to Point Charge Using calculus it can be shown that the electric potential a distance r from a single point charge q is Assuming that potential is zero at infinity 17. 5

Electric Charge and Electric Field 17. 7 Capacitance

Capacitance Capacitor – device that stores electric charge In RAM, Camera Flash, 17. 7

Capacitance Simple capacitors consist of two plate The symbol for a capacitor is The symbol for a cell is The symbol for a battery is 17. 7

Capacitance When a potential difference is placed across a capacitor it becomes charged Charging a Capacitor This process takes a short amount of time Time for RC Circuit The charge on each plate is the same, but opposite charge The amount of charge is proportional to the potential difference A constant C (Capacitance) gives 17. 7

Capacitance – Unit Farad For a parallel plate capacitor, the capacitance depends on the area of the plates, the distance between the plates 17. 7

Electric Charge and Electric Field 17. 8 Dielectrics

Dielectrics Most capacitors have an insulator between the plates Called a Dielectric Increases the capacitance by a factor K Called the dielectric constant 17. 8

Dielectrics Some Dielectric Constants Material K Paper 3. 7 Glass 5 Rubber 6. 7 Mica 7 Strontium Titanate 300 17. 8

Electric Charge and Electric Field 17. 9 Storage of Electric Energy

Storage of Electric Energy A charged capacitor stores energy 17. 9