Ohms Law
Overview
Ohms law describes an important relationship between voltage, current and resistance. Current is rate of flow of electrons which make your circuits work. Voltage represents a pressure moving current forward. Resistance represents an opposing pressure limiting the flow of current. In a wire you can imagine, voltage pushing current forward and resistance pushing current back. The total flow or current is proportional to the voltage and inversly proportional to the resistance. This relationship is called Ohms law and is represented as follows.
V/R = I
V represents voltage. R respresents resistance and I represents current. The I comes from the French for current. It also important that the units of measurement for Ohm’s law are Volts for voltage, Ohms for resistance and Amps for current. In this class we normally talk about Ohms law in the following format.
V = IR.
Exercise
Using Ohm’s law you can easily calculate voltage, resistance or current given any two of the three. Calculate the missing values in the table below. Copy and complete the following table in your notebook. Noee that the last row contains the units milliamps, so you wil need to convert this unit to amps before using Ohms law. Please round any fractions to the nearest thousandth.
Circuit |
Voltage |
Current |
Resistance |
---|---|---|---|
1 |
5.00 Volts |
100 Ohms |
|
2 |
3.00 Volts |
.020 Amps |
|
3 |
.005 Amps |
330 Ohms |
|
4 |
12.00 Volts |
.400 Amps |
|
5 |
1.80 Volts |
470 Ohms |
|
6 |
.250 Amps |
1000 Ohms |
|
7 |
30 milliamps |
330 Ohms |