# COMMUNITY : FORUMS : TECH

## Resistor Voltage Drop

Is there any way to calculate the voltage drop of a resistor value? For example, if I had a 47 ohm resistor, would its voltage drop equal -30V, -857358V, or -0.5V?

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westfw9 years ago
A zener diode will cause a (more or less) fixed voltage drop regardless of current through it, up until the time that it is destroyed. (of course, resisstors are also subject to burning out under similar circucumstances...) (Note also that this is not the way that zener diodes are USUALLY used...)
puffyfluff (author)  westfw9 years ago
Really? I did not know Zeners could do that.
tech-king9 years ago
depends on how many amps you are drawing
puffyfluff (author)  tech-king9 years ago
Unfortunately, I have no way of knowing how much current is being drawn.
uguy9 years ago
Ohm's law explain the relationship of Volts, amps and resistance.
V=IR
The voltage across a resistance is directly related to the current passing through it.
A 47 ohm resistor could conceivably have each of those three voltage drops in three different circuits.