文档介绍：Reading 4 Ron Bertrand VK2DQ
OHMS LAW
Ohm's Law describes the relationship between current, voltage and resistance in an
electric circuit.
Ohm’s Law states:
The current in a circuit is directly proportional to voltage and inversely proportional
to resistance.
Let:
I = current
E = voltage
R = resistance
Part of Ohms Law says: current is directly proportional to voltage.
Using the symbols given, we can write an equation to show a direct proportion between
current and voltage.
I = E
Normally the above equation is read I 'equals' E. It can just as easily and more
understandably be read as: I is directly proportional to E.
I know I harp on the direct proportion and inverse proportion stuff a lot. I do so because it
is so important to thoroughly understand this when e to plex equations.
I = E
Means that if the voltage is increased or decreased in a circuit then the current will
increase or decrease by the same amount. Double the voltage and you double the current.
Halve the voltage and you halve the current. This is a direct proportion.
The other part of Ohm's Law says that current is inversely proportional to the resistance.
This can be written as:
I = 1/R
Now 1/R is a fraction with a numerator (the top part, 1) and a denominator, R.
1/R is a fraction just like 1/4, 1/2