# Electric Circuits Flashcards

Kirchhoff’s First Law

The sum of the currents flowing into a point equals the sum of the currents flowing out of that point

Resistor Series

R = R1 + R2 + R3

Resistor in parallel

1/R = 1/R1 + 1/R2 + 1/R3

Resistor Series Deriving

V = V1+V2+V3 in parallel which equals:

IR = IR1+IR2+IR3

If current is the same everywhere in series it is cancelled out

R=R1+R2+R3

Resistors in parallel Deriving

I = I1+I2+I3 in parallel which equals:

V/R = V/R1+V/R2+V/R3

If voltage is the same everywhere in parallel it is cancelled out

1/R = 1/R1+1/R2+1/R3

Current in Series

I = I1 = I2 = I3

Current in parallel

I = I1+I2+I3

Voltage in Series

V = V1+V2+V3

Voltage in parallel

V = V1 = V2 = V3

Potential Dividers

Used to vary voltage in circuits

Voltage out equation

Vout = Vin x R1/R2+R3

Negative Temperature coefficient

the resistance of conducting material decreases as temperature rises

vibrating ions get in the way of electrons

Positive Temperature coefficient

the resistance of conducting material increases as temperature rises

electrons are ripped from atoms because such high energy causing greater electron flow

Variable Resistors

Used to control current or voltage

Electromotive force EMF

The electrical potential energy transferred from other forms, per coulomb of charge that passes through the source