Tuesday, December 23, 2014

Electric Fractionsssssssss

ELECTRIC FRACTIONS
1 Joule = energy to lift an apple upward by 1 meter
1 Coulomb = 6,000,000,000,000,000,000 electrons 
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Energy to raise m kilograms upward 
by d meters = 10*m*d 

A 90 kg object moved upward by 30 meters has
27,000 Joules of potential energy.
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One banana provides 440,000 Joules
One peanut provides 22,000 Joules
(see wolframalpha.com for other food items)
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Kinetic energy of m kilograms moving 
at v meters per second= (mv^2)/2 
500 kg car going 20m/sec has 
100,000 Joules of kinetic energy.
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3,600,000 Joules costs about 10 cents
from the power company.
1 kilowatt-hour = 1 Kwh = 3,600,000 Joules
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Current is the rate of electron flow.
1 amp = 1 Coulomb/sec
Household current is often 
between 15 amps and 30 amps.
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Voltage is the energy per electron
1 volt = 1 Joule/Coulomb
US houses usually have 110 volt outlets
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Power is the rate of energy use.
1 watt = 1 Joule/sec
A TV set often has a 300 watt rating.
An electric heater commonly requires 
1000 watts to 1500 watts.
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Resistance is a measure of how difficult
it is for electrons to flow.
1 ohm =1Volt/amp 
Electric conductors that give off heat have 
resistance.
Superconductors give off no heat and have
zero resistance.
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Power is the rate of energy use.
1 watt = 1 joule/sec
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For direct current:
voltage = current * resistance
(volts) = (amps) * (volts/amp)
volts = amps * ohms
V = IR
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power = current * voltage 
(Joules/sec) = (Coulombs/sec) * (Joules/Coulomb)
watts = amps * volts
P = IV
P= I^2 R
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See falstad.com  for an applet to construct
and then watch that circuit in action.
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