NATIONAL TRAINING INSTITUTE LLC

MODULE :

BASICS OF ELECTRICITY

CHAPTER 1:

BASICS OF SERIES AND PARALLEL CIRCUITS

Ref No :

IWE/T/1000/07

ELECTRIC CIRCUITS

An electric circuit provides a complete, closed path for an electric current.

Electricity can only flow through a closed circuit; it cannot flow through an open circuit.

EVERY CIRCUIT MUST HAVE THE FOLLOWING PARTS:

1. Energy source: battery, electric generator, etc.

2. Load or resistance: device that uses the electric energy

3. Wires: Conductor (Copper, Aluminium etc...) which can allow the current through it

4. Switch: opens and closes the circuit

SERIES CIRCUIT

All parts are connected one after another.

If one part fails to operate properly, the current cannot flow to the other parts.

PARALLEL CIRCUIT

Different parts of circuit are on different branches.

If one part does not operate properly, current can still flow through the others.

COMPARISION OF SERIES AND PARALLEL CIRCUITS

SERIES CIRCUIT

PARALLEL CIRCUIT

1

2

3

All components are connected

end-to-end to form only one path for CURRENT to flow through the circuit.

All components are connected between the same two sets of electrically common points, creating multiple paths for CURRENT to flow from one end of the battery to the other

4

Voltage drops add to equal total voltage. V=V1+V2+V3+

All components share the same (equal) current. I=I1=I2=I3=

Resistances add to equal total resistance. R=R1+R2+R3+

All components share the same (equal) voltage. V=V1=V2=V3=

Branch currents add to equal total current. I=I1+I2+I3+

Resistances diminish to

5

6

CURRENT I = V/R

Voltage division formula

Current division formula Current for two parallel branched circuit Is

7

CURRENT I = V/R

Current in three parallel branched circuit Is

ASSESMENT-1

1. Do you think the bulbs in the parallel circuit or the series circuit will burn brighter?

Explain why:

2. If you remove a bulb in your parallel circuit, with the other bulb(s) still light?

Explain why:

3. If you remove a bulb in your series circuit, with the other bulb(s) still light?

Explain why:

4. FILL IN THE CHART WITH THE PHRASES:

Series

Parallel

DEFINITION

PATHS

RESISTANCE

EXAMPLES

USE THESE TO FILL IN TABLE:

Home circuits

One path

Device and switch

All lights connected end to end

Several paths

Decreased with added branches

Connected between the same two sets of common points,

Increases with added branches

5.Tell whether each picture shows a series or parallel circuit

5. How many paths can electricity takes in below circuit?

6. If light 3 burns what happen to the other lights in the circuit?

PARALLEL CIRCUIT

7. How many paths can electricity takes in below circuit?

8. If light 2 burns what happen to the other lights in the circuit?

SERIES CIRCUIT

National Training Institute/IWE/ Series and Parallel circuitsPage 7

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