How to Use It?
To use the calculator, just enter at least any two input values and click calculate to solve for the remaining values. Make sure to reset the calculator after each calculation for the best results.
What is Ohm’s Law?
When it comes to fundamental circuit theories, Ohm’s Law is the most fundamental of them all. This law, formulated by a German physicist named Georg Ohm in 1827, is most likely the first formula that all electrical and electronics engineers learn.
According to Ohm’s Law, voltage (V), current (I), and resistance (R) are all proportional and related to each other. Voltage is the potential difference or electric pressure that causes the electrons to flow in a circuit. Current is the rate of flow of electric charge in a circuit. Resistance is the opposition to the flow of current in a circuit.
Ohm’s Law states that the current flowing through a conductor is directly proportional to the voltage applied across it and inversely proportional to the resistance of the conductor.
This can be mathematically expressed as:
Where:
V is the voltage across the conductor (in volts)
I is the current flowing through the conductor (in amps)
R is the resistance of the conductor (in ohms)
This means that for a constant voltage, a higher resistance will result in a lower current flow. And the opposite is also true; for the same given constant voltage, a lower resistance would result in a higher current flow.
The power dissipated by the circuit can also be calculated using the values in Ohm’s Law. For example, power P in watts (W) equals voltage V in volts (V) multiplied by current I in amps (A):
Another way to express Ohm’s law is using a pie chart that shows the relationship between power (P), voltage (V), current (I), and resistance (R).
Remember that the Ohm’s law formula relates only to materials that are able to induce power, such as metals and ceramic. However, some materials, such as diodes, transistors, light bulbs, thermistors and superconductors, do not obey Ohm’s law; these are called non-ohmic materials. These materials have a nonlinear or variable resistance that depends on factors such as temperature, light intensity, magnetic or electric field.
Example
Let’s consider an example where we have a battery of 9 V connected to a resistor of 100 Ω. Using Ohm’s Law, we can calculate the current flowing through the resistor.
Using Ohm’s law, we can write:
Plugging in the values, we get:
Solving for I, we find:
Therefore, the current flowing through the resistor is 0.09 A or 90 mA.
The power dissipated by the circuit can also be found using the values in Ohm’s Law.
Plugging in the values, we get:
