Voltage drop across resistor

[medical-nerd]

Hiya

Aaaarghhh....

I'm probably having a face palm moment but am having a blank at the moment.

I know how to calculate basic voltage drops using ohm's law by calculating current flow first. But what do I do if current is a known fixed value?

If I have a module that uses e.g  275mA at a supply of 5V, if there is a resistance of 10ohm after the voltage regulator, what is the voltage drop across the resistor?

Cheers

[capt bullshot]

U = I * R

multiply the current by the resistors value

[mikerj]

If I have a module that uses e.g  275mA at a supply of 5V, if there is a resistance of 10ohm after the voltage regulator, what is the voltage drop across the resistor?

At 275mA a 10 ohm resistor will drop 0.275*10=2.75volts.  The problem here is that with the resistor in circuit your load is now only seeing 5-2.75=2.25v, so is unlikely to be taking 275mA any more (unless it's a constant current sink).  Current sensing resistors usually have low values to minimise voltage drop, which may then require amplification to get a useful signal.

[Audioguru]

if there is a resistance of 10ohm after the voltage regulator

Is the 10 ohms resistor in series with the 275mA module? Then the module is not getting 5V and probably is not drawing 275mA anymore.