Chapter 7: Electricity

Part 3: Series and Parallel Circuits

Series CircuitsWhen two or more resistors

Connected one end after another

To form a single path for current flow

Series CircuitsPotential difference from the

battery is shared

Therefore each bulb glows dimly

Series Circuits

Current flow of each bulb is same

Therefore brightness of each bulb is the same

Series CircuitsThe circuit is broken when one bulb

is removed

And the other bulbs go out as well

Parallel CircuitsAll components are connected

With their corresponding ends joined together

To form separate and parallel paths for current flow

Parallel CircuitsEach bulb is connected directly to the battery

Thus each bulb glows brightly

Because each bulb gets the full potential difference

Parallel Circuits

Each bulb has a higher brightness

Than each bulb in a series circuit

Parallel CircuitsThe circuit remains unbroken

If one bulb is removed

So the other two bulbs will remain to work

Compare the Circuits’ CurrentSeries Circuit

A1 A2

X Y

3 Ω 1 ΩCurrent has only one path to flow

Reading on A1 = Reading on A2

Same current flows through each resistors

Parallel Circuit

Current splits into different paths

Reading on A = Reading on A1 + A2

Main current is shared between the two resistors

1 Ω

A1

A2

X

Y

3 Ω

A

Compare the Circuits’ Potential Difference

Series Circuit

Reading on V = Reading of V1 + V2

Potential Difference is shared by the two resistors

Parallel Circuit

Reading on V1 = Reading on V2

Potential difference is the same across each resistor

V1

V2

X

Y

3 Ω

1 ΩV1 V2

X Y

3 Ω 1 Ω

V

Compare the CircuitsSeries Circuit

When one bulb has blown up

The other bulb would not be able to light up

Parallel Circuit

When one bulb has blown up

The other bulb can still light up

Compare the CircuitsSeries Circuit

Dimmer bulbs

Less voltage across each bulb

Parallel Circuit

Brighter bulbs

Higher voltage across each bulb

Less current pass through each bulb Larger current pass through each bulb

Determining Effective ResistanceSeries Circuit

𝐼=𝐼 1=𝐼 2= 𝐼3

Parallel Circuit

𝐼=𝐼 1+𝐼 2+ 𝐼3

𝐼=𝐼 1=𝐼 2= 𝐼3

1𝑅1

+1𝑅2

+1𝑅3

=1𝑅

R1 R2 R3I1 I2 I3

V1 V2 V3

I

V

R1 V1 R2 V2 R3 V3

I

I1 I2 I3

V

Current

Potential Difference

Resistance