How to find the Current through a Resistor

This tool calculates the current (I) in Amperes. Enter the values of

• Resistance in Ohm
• Voltage in Volt

Formula

I = V/R

This is also known as Ohm’s law which states that the current through a conductor (I) with a constant resistance (R) between two points is directly proportional to the voltage (V) across the two points.

Example Calculation

For a voltage value of 5 Volt and resistor value of 2 ohm, the current through the resistor is 2.5 Amperes or Amps.

Background

A resistor is an electrical component that opposes the flow of electric current. It is commonly used to control the amount of current flowing through a circuit.

When resistors are connected in series, the total resistance is equal to the sum of the individual resistors. In a series circuit, the same current flows through each resistor, but the voltage drop across each resistor can be different.

On the other hand, when resistors are connected in parallel, the total resistance is calculated differently. The reciprocal of the total resistance is equal to the sum of the reciprocals of the individual resistors. In a parallel circuit, the voltage drop across each resistor is the same, but the current flowing through each resistor can be different.

By employing Ohm’s Law and understanding the behavior of resistors in series or parallel, we can calculate the equivalent resistance and determine the current and voltage drop across each resistor in a circuit.

Why calculate the current through a resistor?

This is required for a number of applications. One that we have discussed here is to calculate the current through a Light Emitting Diode (LED). The circuit requires a series resistor.