AP Physics 2: Review Guide

Electric Field acts as a property of…

space (FE/q) points in the direction a positive charge would feel force (outwards) and a negative charge would feel force (inwards)

More dense field lines indicate

stronger electric field

E-field VECTORS are

TANGENT to the electric field

Force/Fields from MULTIPLE point charges 

Vector Addition

kq1/r + kq2/r …

Equipotential 

Set of adjacent locations where Voltage is constant, perpendicular with E-fields and points towards decreasing V

E = V/r

ONLY works if r is with or against the field

OTHERWISE SUBDIVIDE INTO COMPONENTS Ex = Vx/r, Ey = Vy/r

Energy Conservation from a point charge

If a charge can freely move when only acted on by electric forces from other charges, energy is conserved

K = -U = -qv

Capacitance depends on…

Geometry, not charge or voltage

K is ——

Kappa, dimensionless with no units

• Prescence of a dielectric REDUCES the electric field within the material by POLARIZING the atoms

• ALSO increases capacitance

Permittivity

a measure of how a material responds to the external electric field

(the material is polarized and reduces the E in the material) 

POLAR, free- electron molecules have larger k and e 

Keep a capacitor connected to a battery

CONSTANT V

Disconnect battery from capacitor

Q is constant

IDEALLY, Capacitors have a…

uniform electric field

Electric field charge is….

The charge of our point 

Voltage is NOT…

a vector, at every point in space around a charge

+charge WILL always make a …

-charge WILL always make a…

+V

-V

PE =

QV

Electric Field Lines always point towards

lower potential

qV =

1/2mv², can use this to find speed

work is zero over a 

CLOSED PATH

If it mentions, gravity and work…

Use mgY, qEy (F = qE substitution)

Work is PATH INDEPENDENT

only depends on the starting and ending position, NOT path between

KE and UE are conserved AND

unable to change energy of ENTIRE system

-, +

high potentials, lower potentials

V in a conductor

V = 0 over any path within the conductor, V is CONSTANT at all points in a conductor when charges are in equilibrium

+Q

-q

hill

well

E-field strength always point towards

decreasing potential

using an equipotential map

use the distance between the equipotential lines and the highest voltage

Energy field into vectors of x and y

E = V/x, split 90 into 30 if possible (from other angle information)

Can use electron volts to make

math easier, if 1/base charge, should instead be numerically EV

Have velocity from plates

qV = 1/2mv²

E = V/R, V = Ex

Formulas NOT on the sheet

½ CV², ½ Q²/2C, 1/2 QV

Switch problem

electrons flow out of/away from positive terminal

Q/e = n to FIND electrons that flow

WILL BE GIVEN C,V