# Electric Circuits Flashcards

1
Q

Kirchhoff’s First Law

A

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

2
Q

Resistor Series

A

R = R1 + R2 + R3

3
Q

Resistor in parallel

A

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

4
Q

Resistor Series Deriving

A

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

5
Q

Resistors in parallel Deriving

A

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

6
Q

Current in Series

A

I = I1 = I2 = I3

7
Q

Current in parallel

A

I = I1+I2+I3

8
Q

Voltage in Series

A

V = V1+V2+V3

9
Q

Voltage in parallel

A

V = V1 = V2 = V3

10
Q

Potential Dividers

A

Used to vary voltage in circuits

11
Q

Voltage out equation

A

Vout = Vin x R1/R2+R3

12
Q

Negative Temperature coefficient

A

the resistance of conducting material decreases as temperature rises

vibrating ions get in the way of electrons

13
Q

Positive Temperature coefficient

A

the resistance of conducting material increases as temperature rises

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

14
Q

Variable Resistors

A

Used to control current or voltage

15
Q

Electromotive force EMF

A

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

16
Q

EMF equation

A

work done = charge x emf

17
Q

Internal Resistance

A

The circuit cell’s resistance

18
Q

Lost volts

A

Voltage lost because of internal resistance

19
Q

Kirchoff’s second law

A

Around any closed loop in a circuit, the sum of the supply (emf) is equal to the sum of the pds in the circuit

Energy is conserved

20
Q

EMF, internal resistance equations

A
```Emf = V + Ir
or
Emf = IR + Ir
or
Emf = I(R + r)```