calculating watts
Post on 23-Feb-2016
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Calculating Watts
Watt Watt Watt?!?!
A watt is the basic unit of power. Power is the rate at which electrical energy is delivered to a circuit. “How many watts?” is a question often asked about speakers, sound systems, hair dryers, and light bulbs.
OHMMMMM….
• Ohms law states that voltage is the product of current and resistance. If you know two of the values, you can calculate the third.
• The power formula is related to Ohms law. Use the power formula to calculate the current flow when a lamp is on.
• The power formula is stated as:
P=E(I)
Where,
P=Power in Watts (W)E=Operating VoltageI=Current in amperes
What is the power for a light bulb with a voltage of 12.6 V and a current of 1.04 A?
P=E(I)P=12.6V(1.04A)=13.1W
Round the wattage to tenths, voltage to tenths, and current to hundredths.
Rewrite the power formula in terms of the current. Solve for I.
Start with P=E(I)Divide both sides by E.
P/E=E(I)/EI=P/E
Calculate the current in a bulb where the voltage is 14.5V and the power is 4.9W:
I=P/E(4.9W)/(14.5V)=0.34A
A 1154 bulb has a double filament. The operating voltage is 6.4 V and the currents are 2.63 A and 0.75 A?
What are the power values for each filament?
For the lower-current filament:P=E(I)=6.4V(0.75A)=4.8W
For the higher-current filament:P=E(I)=6.4V(2.63A)=16.8W
Don’t Get Frustrated!
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