CP Workbook
Electric Power
Printer Friendly Version
Recall that the rate at which energy is converted from one form to another is
power
.
power = energy converted / time
power = (voltage x charge) / time
power = voltage x (charge / time)
power = voltage x current
The unit of power is the
watt
(or kilowatt = 1000 watts).
So in terms of units,
electric power (watts) = current (amperes) x voltage (volts)
Thus,
1 watt = 1 joule / 1 second = 1 ampere x 1 volt
.
What is the power when a voltage of 120 V drives a 2-A current through a device?
What is the current when a 60-W lamp is connected to 120 V?
How much current does a 100-W lamp draw when connected to 120 V?
If part of an electric circuit dissipates energy at 6 W when it draws a current of 3 A, what voltage is impressed across it?
The 100 watt bulb draws more current and must therefore have a thicker filament.
The equation
power = energy
_{converted}
/ time
rearranged gives
energy
_{converted}
= power x time
Explain the difference between a kilowatt and a kilowatt-hour.
One deterrent to burglary is to leave your front porch light on all the time. If your fixture contains a 60-W bulb at 120 V, and your local power utility sells energy at 8 cents per kilowatt-hour, how much will it cost to leave the bulb on for the whole month?
Related Documents
Lab:
CP -
Series and Parallel Circuits
Labs -
Parallel and Series Circuits
Labs -
RC Time Constants
Labs -
Resistance and Resistivity
Labs -
Resistance, Gauge, and Resistivity of Copper Wires
Labs -
Telegraph Project
Labs -
Terminal Voltage of a Lantern Battery
Labs -
Wheatstone Bridge
Resource Lesson:
RL -
A Comparison of RC and RL Circuits
RL -
Ampere's Law
RL -
An Introduction to DC Circuits
RL -
Capacitors and Dielectrics
RL -
Dielectrics: Beyond the Fundamentals
RL -
Electricity and Magnetism Background
RL -
Filaments
RL -
Kirchhoff's Laws: Analyzing Circuits with Two or More Batteries
RL -
Kirchhoff's Laws: Analyzing DC Circuits with Capacitors
RL -
Magnetic Field Along the Axis of a Current Loop
RL -
Magnetism: Current-Carrying Wires
RL -
Meters: Current-Carrying Coils
RL -
Parallel Plate Capacitors
RL -
RC Time Constants
RL -
Torque on a Current-Carrying Loop
Worksheet:
APP -
The Circuit Rider
APP -
The Cycle Shop
CP -
DC Currents
CP -
Ohm's Law
CP -
Parallel Circuits
CP -
Power Production
CP -
Power Transmission
CP -
RIVP Charts #1
CP -
RIVP Charts #2
CP -
Series Circuits
NT -
Brightness
NT -
Light and Heat
NT -
Parallel Circuit
NT -
Series Circuits
NT -
Shock!
WS -
Capacitors - Connected/Disconnected Batteries
WS -
Combinations of Capacitors
WS -
Introduction to R | I | V | P Charts
WS -
Kirchhoff's Laws: DC Circuits with Capacitors
WS -
Kirchhoff's Laws: Sample Circuit
WS -
Resistance, Wattage, and Brightness
TB -
34A: Electric Current
TB -
35A: Series and Parallel
TB -
Advanced Capacitors
TB -
Basic Capacitors
TB -
Basic DC Circuits
TB -
Multiple-Battery Circuits
TB -
Textbook Set #6: Circuits with Multiple Batteries
Paul G. Hewitt
Copyright © 1984-2005
All rights reserved.
Used with written
permission.
PhysicsLAB
HTML conversion
Copyright © 1997-2020
Catharine H. Colwell
All rights reserved.
Mainland High School
Daytona Beach, FL 32114