Table of Contents
Q1.1 What Is Electricity:
The purpose of this task is to introduce students to electricity using scientific language.
CORE CONCEPTS:
Electricity, electric charge, current, atoms, electrons & protons.
Q1.1 CLICK HERE TO SEE / HIDE STUDENT FLIP RESOURCES:
Video: Introduction to Electricity
- IF UNABLE TO ACCESS YOUTUBE VIDEO (requires Flash) TRY:Introduction to Electricity
Video: How Coal-fired Power Plants Work
- IF UNABLE TO ACCESS YOUTUBE VIDEO (requires Flash) TRY:How Power Plants Work
Q1.1 CLICK HERE FOR A SCIENTIFIC EXPLANATION:
CONCEPT: What is electricity?
The scientific definition of electricity, provides a fairly simple answer:
Matter is mainly composed of particles of electricity (of electrons and protons), so electricity is a type of matter (material or stuff).
Electricity is not 'matter' in the everyday sense - it is one of the main components of matter. Electricity has mass, although for electrons, the mass per cubic volume is very small (the electrons of a wire are thousands of times lighter than the copper atoms).
Under the scientists' definition of 'electricity', the electricity supply company does not sell electricity, instead it sells a pumping service: The electricity just vibrates slightly back and forth inside the wires.
Electricity generators don't “generate” this electricity, instead they only pump it.
The metal wires connecting your home, school or business, act like water pipes which come already pre-filled with water (where instead of water, there is the 'electricity'). The electrons come included with the wires at no extra cost: they do NOT come from the electricity company generators.
For that reason, we should now understand that generators DO NOT 'generate' any electricity. Instead, generators act as electricity pumps, and all of the 'electricity' in the national power grid is supplied by the metal of the wires.
- An AC generator forces the electricity of the wires to wiggle back and forth.
- A DC generator (or a battery) forces the electricity to flow continuously in a circle, analgous to a closed-loop drive belt.
One unusual consequence of the scientific definition of electricity, is that electricity is NOT invisible. According to scientists, electricity can be seen with the naked eye - it works like this:
- Because negative electrons and positive protons stick together to make big objects, all big objects that we can see and feel are electrically neutral. The word 'Electrically' means “describing electricity”, and 'neutral' is a word meaning “balanced.” That is why we do not feel objects pushing and pulling on us from a distance as if we had strong magnets in out pockets (like they would pull and push us if everything was electrically charged).
- All big objects are electrically neutral because there is exactly the same amount of positive and negative charge in the world. We could say that the world is exactly balanced, or neutral. This seems very surprising and lucky. Scientists still do not know why this is so, even though they have been studying electricity for a long time.
- Objects are visible because light is reflected by electrons of each atom.
- When we look at a collection of atoms, we see only the atoms' outer shell, we see only the electrons… we can only see the 'electricity'.
- Electricity scatters light, but it also causes colours by vibrating resonantly in response to light waves.
- Conductors look silvery because their internal electricity 'shorts out' the electric part of the light waves, causing mirror-like reflection. The sea of electrons inside a wire looks like a reflective metallic fluid - (does this description remind you of any movie characters?)
So, rather than being invisible, 'electricity' is one of the few components of this stuff (particles) that IS visible. Reference: here
Q1.1 CLICK HERE TO SEE / HIDE EXTRA STUDENT FLIP RESOURCES
ELECTRIC CURRENT IS A FLOW OF ENERGY? Wrong.
Electric current is NOT a flow of energy; it's a flow of charge.
Charge and energy are two very different things. To separate them in your mind, see this list of differences. Reference: http://amasci.com/elect/elefaq1.html#aelist
COME ON, WHAT IS ELECTRICITY, REALLY.
OK OK, enough with the definitions! Here is a simple answer:
There are two main things that flow along wires:
- Electric charge
- Electric energy
- There are several other things that flow as well, but to keep it simple, we'll ignore them.
- Because there are *two* things flowing, we cannot call them both by the name 'electricity'.
- For this reason, we cannot ask 'what is electricity'? (Which one would we be asking about?!)
So, instead we have to ask more specific questions, like these below:
- What is the stuff that flows through a light bulb and comes back out again through the other wire?
- What is the stuff that flows into a light bulb and gets changed entirely into light and heat?
The answer to question #1 is 'ELECTRIC CHARGE'. Charge is a “stuff” that flows through lightbulbs, and it flows around a circuit.
Normally no charge is lost during the operation of a circuit, and no charge is gained. Also, charge flows very slowly, and it can even stop flowing and just sit there inside the wires.
In an AC circuit, charge does not flow gradually forwards, it stays roughly in one place and just wiggles backwards and forwards.
The answer to question #2 is' ELECTRICAL ENERGY'. It's also called “electromagnetic energy”. This energy is also like a “stuff” and it can flow from place to place. It always flows very fast; almost at the speed of light. It can be gained and lost from circuits, such as when a light bulb changes the flow of electrical energy into a flow of light and heat.
Here is a list of differences of these two kinds of “stuff”:
| ELECTRIC CHARGE | ELECTRICAL or ELECTROMAGNETIC (E.M.) ENERGY |
|---|---|
| Flows very slowly, and can even stop. | Always flows incredibly fast, almost at the speed of light. |
| The flow is called “electric current,” measured in Amps. | The flow is called “electric power,” measured in Watts. |
| Flows through light bulbs | Consumed by light bulbs (and converted into light) |
| In AC cables, it wiggles back and forth | In AC cables, it flows continuously forwards |
| Supplied by metals (and by all other conductors) | Supplied by generators, batteries, etc. |
| It's a component of matter | A form of energy |
| Doesn't usually leave a circuit. | A “Source” injects it into a circuit, while a “load” removes it again. |
| Composed of movable charges from conductor atoms | Composed of electromagnetic fields |
| Electrons and protons are particles of CHARGE | Photons are particles of E.M. energy |
| Flows inside of wires | Flows in the space adjacent to wires |
| Generators pump it through themselves | Generators create it |
| Circular flow. It flows around and around the circuit, and never leaves it. | One-way flow, from a “source” to a “load”. |
| VISIBLE: it is the silvery part of a metal | INVISIBLE: the EM energy can only be seen if you use iron filings, etc. |
| Measured in units called Coulombs | Measured in units called Joules |
| Occurs naturally | Produced and sold by electric companies |
| Scientists of old called it “electricity.” | Today, electric companies call it “electricity.” |
Perhaps some pictures would help? Here are two diagrams below. More can be found at Where does the Energy flow?
CHARGE
- CHARGE flows in a circle.
- The flow is measured in Amperes
- It flows inside the wires.
- It's provided by the metal.
- Batteries pump it through themselves.
- None is created, none is ever lost.
E.M. ENERGY
- ENERGY flows from the battery to the resistor.
- The flow is measured in Watts
- It flows in the space outside the wires.
- It's made of invisible fields.
- It's the same as light and radio, but lower in frequency.
- Batteries create it. Electric heaters consume it.
Electric charge flows along wires. So does electromagnetic energy.
If you ask 'what is electricity', the answer is 'which one'?
Q1.4 Which diagram best shows how a simple electrical circuit works:
The core images and explanations are from 2017 Electrical Circuits Curriculum Resources and is thus (as would be expected) somewhat confusing and ambiguous.
Circuits (b) and (d) show correct flow, but the the arrows on the left are smaller size than the arrows on the right - which is supposed to imply that some of the current is 'consumed' by the globe!
Only circuit (d) shows correct connection and current flow.
Q1.4 CLICK HERE TO SEE / HIDE STUDENT FLIP RESOURCES:
MORE STUDENT RESOURCES:
Video: Explaining an Electrical Circuit
- IF UNABLE TO ACCESS YOUTUBE VIDEO (requires Flash) TRY:Explaining an Electrical Circuit
Video: Explaining Electrical Circuit Problems
- IF UNABLE TO ACCESS YOUTUBE VIDEO (requires Flash) TRY:Circuit Problems
Interactive Circuit Software:
Q1.4 CLICK HERE FOR TEACHER & SCIENTIFIC EXPLANATIONS:
EXPLANATION OF THE DIAGRAMS:
- a,f and e - ‘the unipolar model’ – the view that only one wire is actually needed between the battery and the light bulb for there to be a current in the circuit.
- c: - ‘the clashing currents model’ – the view that current ‘flows’ from both terminals of the battery and ‘clashes’ in the light bulb
- b and d - ‘the current consumed model’ – the view that current is ‘used up’ as it ‘goes around’ the circuit so the current ‘flowing towards’ the light bulb is greater than the current ‘flowing away’ from it back to the battery.
- d: - ‘the scientific model’ – the view that the current is the same in both wires.
Q1.7 Which option describes how scientists measure quantity of electricity:
Quantity of electricity is measured in Coulombs (by definition).
Q1.7 CLICK HERE TO SEE / HIDE STUDENT FLIP RESOURCES:
For video & related resources for this question, please see student resources included with next question.
Q1.7 CLICK HERE FOR A SCIENTIFIC EXPLANATION:
THE POPULAR (INCORRECT) DEFINITION:
- Quantities of electricity are measured in Joules or Killowatt Hours (KWH)
- Electrical energy is “The Electricity.” This definition is used by electricity supply companies, and used by people who discuss home energy use and home appliances.
- This is unscientific as, according to the scientific definition, charge is not energy, so electricity is NOT a form of energy.
THE SCIENTIFIC (CORRECT) DEFINITION:
- Quantity of electricity is measured in Coulombs.
- Electric charges are the 'electricity'.
- Electricity is not the flow of electrons: it's the electrons and protons themselves.
- When electricity flows, it is called 'Electric Current'.
Dictionaries often define electricity as
A fundamental entity of nature consisting of negative and positive kinds.
This is a scientific definition, where 'quantity of electricity' means the same as 'quantity of charge'.
In other words, electric charge is a charge of electricity.
Each proton and each electron carries a small bit of electricity. If we say that electricity is the 'flow of the electrons', and not 'the electrons themselves', then we're NOT being scientific.
See how Coulombs & Killowatt Hours are actually measured in answers to next question:
Q1.10 What is an electric charge:
Stuff that flows during an electric current is 'Electric Charge', also called “the Quantity of Electricity”
Q1.10 CLICK HERE TO SEE / HIDE STUDENT FLIP RESOURCES:
Video: The Coulomb - Basics of Electric Charge
- IF UNABLE TO ACCESS YOUTUBE VIDEO (requires Flash) TRY:The Coulomb - Basics of Electric Charge
Video: What is a Killowatt Hour (KWH)
- IF UNABLE TO ACCESS YOUTUBE VIDEO (requires Flash) TRY:What is a Killowatt Hour
Q1.10 CLICK HERE FOR A SCIENTIFIC EXPLANATION:
SCIENTIFIC DEFINITION - ELECTRIC CHARGE:
Electric charge, also called “the Quantity of Electricity,” is a fundamental component of everyday matter:
- Objects are made of molecules and atoms
- Atoms are made of protons, neutrons, and electrons
- The protons and electrons are made in part out of electric charge.
- Electric charge is substance-like - it is real stuff.
- If you have a quantity of charge, you cannot destroy it, you can only move it from place to place.
- A FLOW of 'electric charge' is called 'electric current'.
Imprecise use of language creates 'interesting' problems:
Back in the day when electricity was not so well understood, 'Electric charge' had a different name. It was called 'electricity'. Historically, people said things like 'charge of negative electricity' or 'charge of positive electricity'. They used to say 'electric currents' instead of 'flows of electricity'.
Eventually it became so confusing that everyone agreed to changed the old names that they were using and stopped using the word 'electricity': Today, scientists define and talk about Electricity as being 'electric charge' or simply 'charge'.
If you get confused by something you read or something someone says, it pays to remember that the old definitions are still found in many supposedly authoritative text books - and classrooms.