Download Work in Electrical Systems - Pleasant Grove Middle School

Work in Electrical Systems
Notes 2.3

Forces are applied to
charged objects by
electric fields—electric
fields are created by
other charges. You can’t
see or hear electrical
work, you can only see
the results of the work
because it is converted
into other forms of
energy such as rotation,
light, sound, and heat.
I. Coulombs
A. 1 electron = 1.6 x 10-19 C
B. 1 C = charge of 6.25 x
1018 electrons
C. the net charge of 1
coulomb = 6.25 billion billion
 electrons on the bottom plate
of a capacitor rather than on
the top plate.
II. Work in Electrical Systems
A. E = FE/q (electric field equals force
divided by charge)
B. When a charge is moved in an
electric field, work is done.
C. ΔV = E x d (change in voltage equals
electric field times distance moved)
D. W = ΔV x q (Work equals change in
voltage times charge)—electrical work is the
product of potential difference and charge
moved.
E. 1V = 1 J/C ( One Volt = 1 Joule per
Coulomb)
F. vectors point away from the positive charge
and toward the negative charge—work can be
positive or negative
III. Electric Charge and Current
A. 1A = 1C/s ( One Ampere equals one
Coulomb per second)
B. I = q/Δt (Current equals charge
divided by change in time)
C. 1C = 1 A∙s (1 Coulomb equals 1
ampere∙second)
D. 1 ampere∙hour = 3600 coulombs
IV. Effects of Electrical Work
A. movement
B. thermal energy
C. light
D. sound
V. Efficiency of Electrical Devices
A. E = ow/iw
B. Not all electrical work is converted
into mechanical work; therefore, no
electrical device can ever be 100%
efficient.
VI. Why Use Electricity to Do Work?
A. Produced by:
1. burning coal, gas, or oil to produce
thermal energy
2. thermal energy converts water into
high-pressure steam
3. steam pressure is used to drive turbines
4. turbines drive electrical generators to
produce electricity
B. Reasons for using electricity:
1. affordable
2. can move over long distances
through overhead or underground
wires
3. can be transformed into other
forms of energy and work
4. convenient and easy to use