Chapter 11- Electric Field Lines and Electric Potential

Electric Field Lines

Are vectors used to represent the electric field around a charged object

Rules for drawing electric field lines

• Electric field lines due to a positive source radiate OUTWARDS

• Electric field lines due to a negative sources radiate TOWARDS

More rules

• The field lines must be tangent to the direction of the field at any point

• The greater the line density, the greater the magnitude of the field

• Lines always START FROM positively charged objects and END ON negatively charged objects

• The lines must NEVER cross

Conductors and Electric Field Lines

Charged objects will disperse their charges evenly around the conductor

In parallel plates…

the electric field lines ONLY exist between the two plates

Electric Potential Energy

The energy stored in a system of 2 charges a certain distance apart.

• E = W = Fd

Electric Potential (AKA Voltage)

The electric potential energy stored per unit charge at a given point in an electric field

To determine the electric potential at a location:

V = Ep / q

• V= electric potential (Volts or V)

• Ep = Electric potential energy (J)

• q = magnitude of charge (C)

To determine electric potential difference:

V = Vf- Vi

Or

delta V = delta Ep / q

Electron volt

A quantity of energy an electron gains or loses when passing through a potential difference of exactly 1V

eV = 1.60 × 10^-19 J

To determine the electric field BETWEEN 2 charged PLATES

E = delta V / delta d

• E = magnitude of the electric field in V/m

• V = electric potential difference between 2 charged plates (V)

• d = distance between the plates (m)