Guide
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BackgroundKnowledge
Electricity and Ohms Law
Electricity is the flow of charge called electrons. When describing electrical circuits, three terms are used
– voltage, current, and resistance.
Voltage relates to how much potential there is between the positive and negative ends. It is measured
in volts.
Current is a measurement of how many electrons are moving through a conductor. It is measured in
amps.
Resistance is how difficult it is for the electricity to flow through the conductor. It is measure in ohms.
It can be difficult to visualize these concepts. So, a more tangible
example is to think of water instead of electrons. Think of a
water tower – it holds water high up in the air, which gives the
water a potential. This is like voltage.
Imagine there are two pipes going from the top of the water
tower to the ground - one that was big and one that is small. If
you had to fill up a bucket with water, would you put the bucket
under the big pipe or the small one? You would choose the big
pipe because it would fill much faster. This is like the current,
similar to the amount of water flowing.
If you’d measure the amount of water going through the pipes,
you’d notice that there is less water flowing through the smaller
pipe than the big one. It is harder to push water down a smaller
pipe than a large one. This is like resistance – the bigger the pipe,
the less resistance.
In electricity, these three concepts work the same way but instead of pipes and flowing water, we have
conductors carrying electrical current. The three principles are related by Ohms Law:
(
)
=
(
)
∗ ()
Which can also be written as: =
=
The water analogy still works with Ohms law – basically the higher the water height (higher voltage) and
the bigger the pipe (less resistance), the more water flows down the pipe (higher current).