LESSON NOTE
What is power?
Power is
the amount of energy per unit time that is being consumed by a load. Power is the product of voltage times
current.
Power = Voltage x Current
P = V x I
What are the units of power?
Power is
measured in Watts (W) or in Joules per second (J/s).
How is 1 Watt the same
as 1 Joule per second?
We can say
that a Watt is Volt x Amp
1 Watt = 1 Volt x 1 Amp
We also
know the following:
1 amp = 1 Coulomb / second
1 volt = 1 Joule / Coulomb
By
combining the three equalities above, we get
1 Watt = 1 Volt x 1 Amp
1 Watt = (1 Joule / Coulomb) x (1 Coulomb / second)
1 Watt = 1 Joule / second
Therefore, a Watt is a measure of Joules in a second.
How do we calculate the total power in a
circuit?
This is the good news.
Power is calculated the same way in both series and parallel
circuits. Very simply, you add the
power consumption of each load together.
What is energy?
The capacity for doing work. Forms of energy include thermal,
mechanical, electrical, and chemical. Energy may be transformed from one form
into another. Energy is measured in
Joules.
What
is electrical energy?
Power is
electrical energy in a set amount of time.
We can also say that energy is equal to power times time.
E = P x t
Electrical
energy can be measured in Joules but tends to be measured in KiloWatt-Hours.
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