There are a lot of misconceptions regarding electric circuits.
You might be surprised to discover that these five statements are all false.
1. When an electrochemical cell no longer works, it is out of charge and must be recharged before it can be used again.
2. An electrochemical cell can be a source of charge in a circuit. The charge that flows through the circuit originates in the cell.
3. Charge becomes used up as it flows through a circuit. The amount of charge that exits a light bulb is less than the amount that enters the light bulb.
4. Charge flows through circuits at very high speeds. This explains why the light bulb turns on immediately after the wall switch is flipped.
5. The local electrical utility company supplies millions and millions of electrons to our homes everyday.
A battery does not supply the charges, copper wire is composed of charges and the battery merely pumps the negative charges around the circuit. This negative electric charge flows very slowly. Total charge is always conserved and cannot be either created or destroyed.
The energy in electric circuits is not carried by individual electrons. Electric energy travels at close to the speed of light moving along the columns of electrons. The energy is carried by the circuit as a whole and not by the individual charged particles. Electric charge flow and electric energy flow are different things. Electric energy travels in wave form-electron compression waves travel inside the wires, the energy is in the invisible fields surrounding the wires.
The movement of charge injects energy into the whole circuit all at once.These analogies might help-
When we speak the air leaving our mouths travels very slowly whilst the sound waves generated travel at great speed.
If you spin a bicycle wheel every part of the wheel acquires kinetic energy at the same time. If you push at point A on the wheel you will instantly inject energy into the entire wheel. A brake applied at point B will take energy away from the wheel at the same instant that you injected energy at point A. The brake extracts energy from the entire wheel instantly and slows down the wheel in the process. The light bulb in a circuit does the same thing, the bulb slows down all of the electrons in the entire circuit and extracts energy from the entire circuit as it lights up.
In AC circuits the electrons don’t flow forward at all, instead they vibrate slightly. It is the movement of charge that generates the electrical energy.
Children will not understand electricity unless you help them to construct an accurate mental model.
<![CDATA[<a href="http://www.youtube.com/v/jbi7gJTPSXk&rel=1" target="_blank">http://www.youtube.com/v/jbi7gJTPSXk&rel=1</a>]]>Chris.
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