Series and Parallel

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Series and Parallel Circuit Lessons with Activities

Series Circuit vs Parallel Circuit

Parallel Circuit

Series Circuit

A series circuit only has a single pathway for the electrons to move from the negative end of the battery to the positive end.
In the example above if one light goes out the other will go out as well.
A popular example of a series circuit is a string of lights. When one goes out, they will all go out as the electricity no longer has a pathway to follow.

A parallel circuit has multiple pathways for the electrons to flow from the negative end of the battery to the positive end.
In the example above if one light goes out the other light will remain lit.
Our homes and other buildings are wired in parallel. Just imagine if one light went out in the house and they all did.

Insulator vs Conductor

Insulators and conductors are equally important. The insulator is made of a material that does not allow electrons to pass through it. Most wires use insulators made from materials like rubber or plastic. Not only does the material have to prevent electrons from flowing through it, it must not crack or split when being bent or pulled. A crack or split could reveal the conductor which is material that allows electrons to flow through it. Normally this is made of metals such as copper or aluminum. Some higher end electronics would use higher grade metals such as gold or platinum. It is important to note that the more electrons that flow through a wire the bigger the wire must be.

Amps, Voltage, and Resistance

One of the easiest ways to understand electricity is to use an analogy of water running though pipes and a faucet. Voltage is know as the electrical pressure in a circuit. While amps is the measurement of electrons passing a particular point. When working with electricity you must know the value of both volts and amps. Anyway back to the analogy, water in our pipes is always under pressure that was created by a water tower or well pump. The water pressure is voltage. If you are on city water your water is measured using a water meter, it just measures the volume of water that passed through it. In our analogy this is the amps. A faucet would represent a switch, when the faucet is open the water would flow, and when closed the water would stop flowing. Remember the water on the back side of the faucet the water in the pipes is still under pressure. Just like the voltage is still in the wire before a switch. The fountain of water represents power. Power is calculated by multiplying voltage x current (amps).

Ohm's Law
E = volts or pressure
I = current or amps
R = resistance or ohms
P = Power or size of the water fountain.

The red handle is a shut-off valve. When it is perpendicular to the pipe there is no water flowing. When it is parallel to the pipe there is little resistance.

Ohm's Law Explained

Did you know that a static shock can easily be 35,000 volts. That shock did't hurt you because there were hardly any amps behind the shock. If that shock had only 1 amp there would be a lot less people in this world.

Calculating Volts, amps, Ohms, and Power

The chart to the right is useful when calculating an unknown value in a circuit.

I = Amps (Current)
E = Volts
P = Power
R = Ohms

Activity / Lesson

The following activities are to be used under the supervision of a technology instructor. Improper wiring can result in a direct short that can overheat wires. This can lead to burns or fire. Please proceed under close supervision.

Vocabulary

Electricity: The movement of electrons.
Insulator: A material the prevents the movement of electrons
Conductor: A material that allow electrons to flow threw it
Resistor: An object that only allows a certain amount of electricity to flow through it, like a light bulb.
Contact: Where to conductors meet to allow electricity to flow through.
Terminal: A dedicated location for contacts.

Electrical symbols used in this activity

Symbol for Battery

Symbol for Light

Symbol for Wire

Symbol for Nail Head

Schematic of empty activity board.

Activity / Lesson 1 (Create a simple circuit)

The first circuit you will make is a simple circuit containing the battery pack, one light and two wires. Simply use the wires with alligator clips to make the circuit between the terminals (nails). This activity will verify the the batteries are in good working condition. The light should light up nice and bright when you do this if it does not you need to troubleshoot the circuit. Make sure you followed the diagram exactly. Make sure the light bulb is screwed in all the way. Wiggle the alligator clips to see if they are making a good connection. If none of this works take it to your teacher for help.

Simple circuit with a battery, wires and one light.

Activity / Lesson 2 (Conductor vs Insulator)

In this activity you explore the electrical properties of certain materials. You will need to add one wire to the circuit that you just made. Notice the question mark in the electrical schematic to the right. This is where you will insert the list of materials below one at a time. If the light bulb lights up it means that electricity was able to pass through it making it a conductor. If the light bulb does not light up it means that it is an insulator. Please note which materials are insulators and which are conductors.

Place following into the circuit to see if it a conductor or and insulator.

String
Wood
Nail
Paper
Aluminum Foil
Plastic
Coated Paper Clips
Metal Paper Clip

Experiment with conductors and insulators by using this simple circuit.

Questions for activity 2

Of the materials tested what ones are insulators?
What could an insulator be used for?
Does an insulator allow electrons to move through it?
Of the materials tested what ones are conductors?
What could a conductor be used for?
Does a conductor allow electrons to move through it?
What do all the conductors have in common?

Activity / Lesson 3 (Series Circuit)

You will need to rewire your activity board to match the electrical schematic to the right. You will be creating a series circuit. A series circuit is a circuit that only allows the electrons to flow through a single path. Try this, place your finger on one side of the battery and follow the electrical path. You will see that there is only one way for the electrons to flow. Before changing the circuit for the next activity take a mental note of the brightness of the lights.

Questions for activity 3

With the circuit on and both lights lit, unscrew a light bulb A. In this series circuit what happens to light bulb B?

With the circuit on and both lights lit, unscrew a light bulb B. In this series circuit what happens to light bulb A?
Why does the remaining bulb go out?
What is the definition of a series circuit?

Basic series circuit with a battery, wires and two lights.

Activity /Lesson 4 (Series Circuit continued)

Add two more lights to your series circuit be following the electrical schematic to your right. If the last wire is not long enough to reach across the board simple clip two wires together. Make sure that the exposed alligator clip does not come in contact with any other conductors (exposed wires or nails)

Questions for Activity 4

Are all the bulbs lit?
Are the bulbs lit equally?
Are the bulbs brighter or dimmer then in the last activity?
What happens when you unscrew one of the bulbs in a series circuit?

Series circuit with a battery, wires and four lights.

Activity / Lesson 5 (Parallel Circuits)

Rewire your activity board to match the electrical schematic to the right. Both lights should be lit if done properly. You have just wired a parallel circuit. A parallel circuit is a circuit that has multiple pathways for the electrons to flow. Place your finger at one end of the battery and follow the circuit. You will see that there is more then just one path for the electrons to take to get back to the other end of the battery.

Questions for Activity 5

What is a parallel circuit?
With the circuit on and both bulbs lit, unscrew light bulb A. What happens when you unscrew light bulb B from this parallel circuit?
Does the brightness of the remaining bulb change?
With the circuit on and both bulbs lit, unscrew light bulb B. What happens when you unscrew light bulb B from the parallel circuit?
Does the brightness of the remaining bulb change?
How is this different from a series circuit?

Basic Parallel Circuit with a battery, wires, and two lights.

Activity / Lesson 6 (Parallel Circuits Continued)
Rewire your activity board to match the electrical schematic to the right. You are simple adding two more lights to activity 5. You may do this with the lights on. While attaching the wires note any changes in the brightness of the lights.

Question for Activity 5

As you added lights C and D did Lights A and B change in brightness?
When you unscrew a bulb in a parallel circuit what happens to the other lights in that circuit?
If you compare the brightness of the lights in a parallel circuit to those in a series circuit which are brighter?

Parallel Circuit with a battery, wires, and four lights.

Activity / Lesson 7 (Series and Parallel Circuits)
Rewire your activity board to match the electrical schematic to the right. Again if the wire going from light d back to the battery pack isn't long enough connect two wires together, and make sure the exposed alligator clip does not come in contact with any other conductor.

Questions for Activity 7
Which lights are brighter? Why?
Which lights are dimmer? why?
If you only unscrew light bulb A what happens to the rest of the bulbs? Why?
Will the same happen with light bulb B? Why?
If you only unscrew light bulb C what happens to the rest of the bulbs? Why?

Series and Parallel Circuits on the same activity board.