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Simple Electricity. By Christos. The Enormous Electrical Force. Quiz: If you were standing at a arm’s length from someone and each of you had an 1% more electron than protons the repelling force would be as great to lift: The Big Ben? The Mount Everest?
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Simple Electricity By Christos
The Enormous Electrical Force • Quiz: If you were standing at a arm’s length from someone and each of you had an 1% more electron than protons the repelling force would be as great to lift: • The Big Ben? • The Mount Everest? • A weight equal to that of the entire Earth? R. P. Feynman in the Feynman Lectures on Physics
electromotive force (EMF) or Voltage is the pressure that forces electrons to flow through a circuit as water pressure forces the water to flow
Current is the flow of electrons in an electric circuit as when water flows through a pipethere is a current
Water is limited by the amount of friction it encounters as it flows. Electricity is limited by the amount of resistance it meets as it passes through a circuit.
Series Circuit • http://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/DC-Current/gifs/SimpleSeries3.gif
Parallel Circuit • http://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/DC-Current/gifs/SimpleParallel.gif
OK, so electricity is exactly like water flow? • Well not exactly : • Any time a battery is connected in a closed circuit is “turned on” unlike a water pipe system in which the pump can be turned on and off even if the pipes make a complete circuit. • If only gravity is causing the fluid to flow then water can flow out of the end of open pipe where as electrical charge will not flow out of an electrical socket. Gravity is always turned on where as the electrical potential is not turned on until the circuit makes a closed loop.
Current Law • The electric current in amperes which flows into any junction in an electric circuit is equal to the current which flows out. This can be seen to be just a statement of conservation of charge. Since you do not lose any charge during the flow process around the circuit, the total current in any cross-section of the circuit is the same
Voltage Law • The voltage changes around any closed loop must sum to zero. No matter what path you take through an electric circuit, if you return to your starting point you must measure the same voltage, constraining the net change around the loop to be zero. Since voltage is electric potential energy per unit charge, the voltage law can be seen to be a consequence of conservation of energy.
And an easy peasy quiz • http://www.ac.wwu.edu/~vawter/PhysicsNet/QTMovies/DC-Circuits/DC-SwitchMain.html