electric bills

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ELECTRIC BILLS YOUR ELECTRIC BILL

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ELECTRIC BILLS. YOUR ELECTRIC BILL. Cost of Electrical Energy. Energy = W = Pt Unit: Joules or kWhr 1kWhr = 3.6 x 10 6 J *The electric company uses the kWhr due to the large amount of energy used in the home. EXAMPLE:. A television draws 5.0Amps of current when operated on 120V. - PowerPoint PPT Presentation

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Page 1: ELECTRIC BILLS

ELECTRIC BILLS

YOUR ELECTRIC BILL

Page 2: ELECTRIC BILLS

Cost of Electrical Energy Energy = W = Pt

Unit: Joules or kWhr

1kWhr = 3.6 x 106J

*The electric company uses the kWhr due to the large amount of energy used in the home.

Page 3: ELECTRIC BILLS

EXAMPLE: A television draws 5.0Amps of current

when operated on 120V.

a) What is the power rating of the television?

P = VI

P = 120V(5Amps)

P = 600W =0.6kW

Page 4: ELECTRIC BILLS

B) What amount of energy is consumed by the television over 30, 5hr days?

W=Pt

W= 0.6kW(30days)(5hr/day)

W= 90kWhr

C) At $.11 per kWhr, what is the cost of operating the television for this time?

cost = 90kWhr( $.11/kWhr)

cost = $9.90

Page 5: ELECTRIC BILLS

You pay for electrical energy measured in kWhr.

Page 6: ELECTRIC BILLS
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SHORT CIRCUITS

A circuit that has little to no resistance.

Current always takes the path of least resistance. The current in the extra wire across R1 will bypass the resistor.

Page 8: ELECTRIC BILLS

SAFETYToo many resistances in parallel will decrease the total resistance to a very low level. This creates a short circuit.

Page 9: ELECTRIC BILLS

Circuit breakers

If current is too high a circuit breaker will mechanically open the circuit and stop the flow of current.

Page 10: ELECTRIC BILLS

FUSES

If current is too high, it melts a thin piece of wire in the fuse which stops the flow of current.