{{:electricity:electricity-banner-790x50.jpg|Electricity Banner}}
====== Q4.1 + Q4.3 What is the stuff that flows through a light bulb: ======

=== CORE CONCEPTS: ===
  * Q1: What is the stuff that flows through a light bulb and comes back out again through the other wire?
  * Q2: What is the stuff that flows into a light bulb and gets changed entirely into light and heat?

++++ Q4.1 & Q4.3 CLICK HERE TO SEE / HIDE STUDENT FLIP RESOURCES:|
No video resources available yet for this question.
Please see the SCIENTIFIC EXPLANATION below:

----
++++

++++ Q4.1 & Q4.3 CLICK HERE FOR A SCIENTIFIC EXPLANATION:|
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, to avoid confusion, 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:
  - Q1: What is the stuff/substance that flows through a light bulb and comes back out again through the other wire?
  - Q2: What is the stuff/substance 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 Alternating Current (AC) circuit, charge does not flow forwards at all, instead it sits in one place and wiggles forwards and backwards around a common point.

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.

As far as elementary textbooks are concerned, we have no name for the thing which flows inside of wires.

This entity, whenever it is flowing, is properly called “an electrical current.” But when the stuff *stops* flowing, what do we call it?

It's still inside the wire of course. But it's not moving anymore.

Refer to advanced physics texts, and there we'll find its correct name: 'Charge'.

An electric current is 'a flow of charge'.

Yet the K-6 books never mention this. Instead they say that 'current flows'. They repeat this over and over... and over! Students are very lucky if they avoid picking up the wrong idea that the charges vanish when the flow is halted. (Does the water in a pipe suddenly evaporate when you halt its flow? No, and neither do the flowing charges within a metal wire. The “current” is gone, but the charges just stopped in place.) 

----
++++

++++ Q4.1 & Q4.3  CLICK HERE FOR A SCIENTIFIC EXPLANATION ABOUT ELECTRIC CURRENT:|
Most K-12 textbooks discuss a substance (stuff), or energy called “current”.

The books and other resources constantly talk about 'flows of current', but this makes no sense.

By way of explanation, here's a pointed question:

Question #1:  What flows in rivers?

Answer to #1: Ummm... is it 'water', or is it 'current'?

If I fill a bucket from the river, do I have a bucket full of 'current'? No!

It is only the water that actually moves: Water flows in pipes, not 'current'.

A 'flow of water' is a correct phrase, while a 'flow of current' is not correct.

The same idea applies to electricity: electric current is a flow of a substance (stuff), but the name of the substance is not 'current' - it is better spoken of as being 'charge'.

  Since a current is a flow of 'charge', the common expression 'flow of current'
  should be avoided, since literally it means 'flow of charge'.

Reference: Modern College Physics: Sears, Wehr, & Zemanski 

OK - SO 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

----

++++