Download Presentation on basic electricity

Simple Electricity
By Christos
The Enormous Electrical Force
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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
Water – Circuit Analogy
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 pipe there 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/~vawt
er/PhysicsNet/Topics/DCCurrent/gifs/SimpleSeries3.gi
f
Parallel Circuit
•
http://www.ac.wwu.edu/~vawter/P
hysicsNet/Topics/DCCurrent/gifs/SimpleParallel.gif
OK, so electricity is exactly like
water flow?
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Well not exactly :
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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
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http://www.ac.wwu.edu/~vawter/PhysicsNet
/QTMovies/DC-Circuits/DCSwitchMain.html