By Michelle Labbe – Updated March 24, 2022

The voltage of a battery is the driving force that pushes electrons through a circuit, representing the potential energy available to move electrons from one point to another. While resistance—a natural opposition to electron flow—can impede this movement, the amount of voltage a battery can provide is easily determined with a standard formula used by electrical engineers worldwide.

Step 1

Write out the voltage formula, which comes from Ohm’s Law:

Voltage (E) = Current (I) × Resistance (R), or simply E = IR.

Step 2

Insert the known values for current and resistance into the equation. Current is measured in amperes (A) and resistance in ohms (Ω). For example, if the current is 6 A and the resistance is 3 Ω, the equation becomes:

E = (3 Ω)(6 A)

Step 3

Solve the expression to find the voltage. Using the example above, the battery must supply:

E = 18 V

Thus, a 6‑ampere current flowing through a 3‑ohm resistor requires a battery voltage of 18 volts.