electric fields

Capacitance

Ratio of charge and potential difference

Line of force in an electric field

Direction of force on a charge. Charge is positive.

Electric potential at a point

Work done moving unit positive charge from infinity to the point

Electric field

F/q = v/d

Work formula

W = qEd

F = Eq

Voltage at a specific point formula

V = kQ/r

E = kQ/r²

k constant

9×10^9

Capacitance formula

Q = cv

Q = charge

C = capacitance

V = voltage

Number of electrons

Charge / charge of electrons

Factors affecting capacitance

1. Area

2. Distance

3. Permitivity

Capacitors in series

have the same charge as the total effective Qt

Voltage in series

Adds

Capacitors in parallel have charge

that adds to make the total effective Qt

Voltage in parallel

Is the same

Time constant

Resistance x capacitance

Voltage time constant formula

V = V0 e^-(t/RC)

Discharging means

going DOWN 63% to 37%

Charging means

Going up 63% to 37%

How many percent of Vo to find V

37%Vo

time constant formula

t = -Rcln(V/Vo)

Capacitance is

Usually really small

Motor effect force formula

F = BILsinθ

Force on a moving charge

F = BQV

Hall voltage

Vh = BI / nte

potential energy for capacitors

E = 1/2qV

E = 1/2CV²