How to convert Ohms to Volts

How to convert resistance in ohms (Ω) to electrical voltage in volts (V).

It is possible to calculate volts from ohms and watts or amps, but you cannot convert ohms to volts since ohm and volt units do not measure the same quantity.

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Ohms to Volts calculation with amps

In accordance with Ohm's Law, the voltage V in volts (V) is equal to the current I in amps (A) times the resistance R in ohms (Ω):

V_(V) = I_(A) * R_(Ω)

So volts are equal to amps times ohms:

Volts = Amps * Ohms

or

V = A * Ω

Example

Find the voltage in volts given a resistance of 25 ohms and a current of 0.2 amps.

The voltage V is equal to 0.2 amps times 25 ohms which is equal to 5 volts:

V = 0.2A * 25Ω = 5V

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Ohms to Volts calculation with Watts

The power P is equal to the voltage V times the current I:

P = V * I

The current I is equal to the voltage V divided by the resistance R (ohm's law):

I = V / R

So the power P is equal to:

P = V * V / R = V² / R

So the voltage V in volts (V) is equal to the square root of the power P in watts (W) times the resistance R in ohms (Ω):

V_(V) = √[P_(W) * R_(Ω)]

So volts are equal to the square root of watts times ohms:

Volts = √[Watts * Ohms]

or

V = √[W * Ω]

Example

Find the voltage V in volts given a resistance of 12.5Ω and a power of 2 watts.

The voltage V is equal to the square root of 2 watts times 12.5 ohms which is equal to 5 volts:

V = √[2W / 12.5Ω] = 5V

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