1.
Part II: Electrical Systems 4.What is the difference between power and energy? (5 points) 5.
Where does one put the service entrance for a building? (5 points) 6.What is the best practice in
laying out electrical circuits in residential or commercial buildings? (5 points)
Solution
Energy
Power
P
Energy is the capability to do something. For example, energy is used for moving the car or
heating the home or lighting the night or even flying an aeroplane. The basic unit of Energy is
Joule but normally it is termed in watt-hour or kilowatt-hour. Energy appears in many forms and
is often expressed in multiple units.
Coming to power, it is rate of Energy per unit of time. Power is the capacity of energy, which is
being used. In more simple terms, power is defined as the rate of doing work. Power finds it use
in mechanical applications, heat applications, electrical applications and several other areas.
b)
Let
Energy Power
Definition
Energy is the capacity to do work. Energy is power
integrated over time.
Power is the
rate at which
work is done,
or energy is
transmitted.
Unit joules = watt-seconds
watt =
joules/second
Common symbol(s) W P