Electric Circuits

Question 1

Kirchhoff’s First Law

Answer 1

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

Question 2

Resistor Series

Answer 2

R = R1 + R2 + R3

Question 3

Resistor in parallel

Answer 3

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

Question 4

Resistor Series Deriving

Answer 4

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

Question 5

Resistors in parallel Deriving

Answer 5

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

Question 6

Current in Series

Answer 6

I = I1 = I2 = I3

Question 7

Current in parallel

Answer 7

I = I1+I2+I3

Question 8

Voltage in Series

Answer 8

V = V1+V2+V3

Question 9

Voltage in parallel

Answer 9

V = V1 = V2 = V3

Question 10

Potential Dividers

Answer 10

Used to vary voltage in circuits

Question 11

Voltage out equation

Answer 11

Vout = Vin x R1/R2+R3

Question 12

Negative Temperature coefficient

Answer 12

the resistance of conducting material decreases as temperature rises

vibrating ions get in the way of electrons

Question 13

Positive Temperature coefficient

Answer 13

the resistance of conducting material increases as temperature rises

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

Question 14

Variable Resistors

Answer 14

Used to control current or voltage

Question 15

Electromotive force EMF

Answer 15

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

Question 16

EMF equation

Answer 16

work done = charge x emf

Question 17

Internal Resistance

Answer 17

The circuit cell’s resistance

Question 18

Lost volts

Answer 18

Voltage lost because of internal resistance

Question 19

Kirchoff’s second law

Answer 19

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

Question 20

EMF, internal resistance equations

Answer 20

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