• In mechanics, power?P?is defined as the?rate of doing work
  • The potential difference is the?work done per unit charge
  • Current is the?rate of flow of charge

   

• Therefore, the electrical power is defined as the?rate of change of work done:

• The work done is the energy transferred so the power is the?energy transferred per second?in an electrical component

• The power dissipated (produced) by an electrical device can also be written as

• Using Ohm's Law?V?=?IR?to rearrange for either?V?or?I?and substituting into the power equation, means power can be written in terms of resistance?R

• This means for a given resistor if the current or voltage?doubles?the power will be?four?times as great.
  • Which equation to use will depend on whether the value of current or voltage has been given in the question

   

• Rearranging the energy and power equation, the energy can be written as:

E?=?VIt

• Where:
  • E?= energy transferred (J)
  • V?= voltage (V)
  • I =?current (A)
  • t?= time (s)

   

ANSWER:? ?A