SERIES CIRCUITSPrinciples of Physics

Simple Circuit

A circuit with one resistor When one electron leaves the voltage supply another one enters

How fast this exchange occurs is based on resistance

One electron pushes another and so on

Series Circuit

More than one resistor in a single path

Each electron must go through every resistor

Total resistance increases with every resistor added in series

Resistor in Series

Current in a Series Circuit

Current flow depends on all resistors

Current through each resistor is the same

IT = I1 = I2 = …

R1

R2

Remember, Voltage is Lost in Resistors

A voltage exists across every device (voltage supply, resistors, light bulbs, etc.)

As an electron goes through a resistor or device it loses energy because it does work to get through

How much energy lost per Coulomb (voltage) depends on the resistance

Voltage in a Series Circuit

Voltage gained by electrons when leaving the voltage supply equals the total voltage lost before returning

Since voltage is lost through all resistors

VT = V1

+ V2 + …

R1

R2

Total Resistance in a Series Circuit

To determine the current leaving the voltage supply the total resistance must be used

RT = R1 + R2 +…

R1

R2

Analyzing a Series Circuit

Determine the total current in the circuit

V = IR12 V = I(24 Ω)

I = 0.5 A

10 Ω

14 Ω

12 VRT = R1 + R2

= 10 Ω + 14 Ω = 24 Ω

Analyzing a Series Circuit

Determine the voltage in the 10 Ω resistor

V = IRV= 0.5 A(10 Ω)

V = 5 V

10 Ω

14 Ω

12 V

Analyzing a Series Circuit

Determine the voltage in the 14 Ω resistor

V = IRV= 0.5 A(14 Ω)

V = 7 V

10 Ω

14 Ω

12 Vor VT = V1 + V2

12 V = 5 V + V2

V2 = 7 V

Comparing Circuits with Series Resistors

5 Ω

5 Ω

12 V

5 Ω

5 Ω

12 V5 Ω

A B

By adding another resistor in seriesIncrease total resistanceDecreases currentVoltage across each resistor decreases

Resistors in Series

Adding a resistor in series increases the total resistance

When one resistor is disconnected the circuit is open – current does not flow

Everyone has to go through all doors to get out The smallest door slows the movement the

most