07_AC_electricity

01 amps for one bulb giving p i2r 001220 20 10 4 watts

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Unformatted text preview: ered to the house draws only I = 120 Watts/12 kV = 0.01 Amps for one bulb, giving P = I2R = (0.01)220 = 20 10 4 Watts, so P = 0.002 Watts of power dissipated in transmission line Efficiency in this case is = 120 Watts/120.004 = 99.996% Winter 2008 4 1 AC Electricity 02/07/2008 UCSD: Physics 121; 2008 DANGER! UCSD: Physics 121; 2008 A way to provide high efficiency, safe low voltage: • But having high voltage in each household is a recipe for disaster – sparks every time you plug something in – risk of fire – not cat-friendly step-up to 500,000 V step-down, back to 5,000 V ~5,000 Volts • Need a way to step-up/step-down voltage at will – can’t do this with DC, so go to AC step-down to 120 V High Voltage Transmission Lines Low Voltage to Consumers Winter 2008 5 Winter 2008 6 UCSD: Physics 121; 2008 UCSD: Physics 121...
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This note was uploaded on 01/30/2014 for the course PHYS 121 taught by Professor Staff during the Winter '08 term at UCSD.

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