What is POWER ? The rate of doing work.
In our first experiment you learned that a bulb was a special conductor which
gets very very hot when electrons flow through it. In fact, the bulb does
this because it is opposing or resisting the electron flow. When this happens
heat is generated.
The more the bulb (or any other conductor) resists or opposes the electron
flow then the more heat may be generated.
Also, if you continue to 'force' more electrons through a conductor by applying
a larger Potential Difference, then more heat will be generated.
When we generate heat like this we say that we are 'dissipating power' -
dissipating means a bit like 'using'. The symbol for power is P and we measure
power in Watts (after a famous scientist called James Watt who was born in
Scotland). Watts is usually shortened to just W.
There is a formula to you can use to calculate the power (or number of Watts)
that are being dissipated in a circuit.
The formula is: P = V x I
This formula shows that the power increases as more electrons or current
(I) flows or you 'force' more current to flow by applying a larger voltage
(V).
If we have say 4 volts (V) and a current of 3 amps (I) then from the formula:
POWER (P) = 4 x 3 answer 12 watts.
There is another formula which can help calculate the relationship between
volts current and resistance
The formula is: V = I x R
There is a graphic of the magic triangle below.
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