Transcript Electrical Power and Energy

Electrical Power and Energy
Electrical Power
• We briefly discussed power (P = W/T), where
P = power, W = Work, and T = Time
– Power was defined as the rate at which work is
done
– Electricity can do work
• Examples: Hair dryers, fans, power tools etc.
• Electrical Power is defined as the rate at which
electrical energy is converted to another form of energy
Calculating Power
• Electrical Power just like power is measured in
Watts
• The amount of power used by an appliance is
calculated as:
Power = Current x Voltage
or
Watts = Amperes x Volts
or
P=IxV
Example
• A calculator has a 0.01 A current flowing
though it. It operates with a potential
difference of 9 V. How much power does it
use?
– What do we know? P = I x V
• P=?
I = 0.01A
P = 0.01A x 9V
P = 0.09W
V = 9V
Another Example
• A microwave oven uses 1000 W of power. The
voltage source is 120 V. What is the current
flowing through the microwave?
• P = I x V, however we need to calculate for I
• I = P/V
• I = 1000W/ 120V
• I = 8.3A