electronics math formula

Vout=[R1/(R2+R1)]Vin

where

Vin/(R2+R1)=Itotal

therefore

Vout=R1Itotal

This is resistance in a series, where you know the reference voltage on one side and the resistance of each resistor, you can determine the voltage drop across the first resistor.

Thank you for the reply!

The formula i am looking for pertains to an OP-AMP circuit. I need to amplify an analog voltage with a 1:2 ratio. in other words for each volt in I need 2 vols out per. The supply volt is 12 VDC, analog volts in, 0.2 to 4.7

Is the 1 in this equation the voltage max out?

Thanks Dave

Is the 1 in this equation the voltage max out?

No, it just means that the gain (Vout/Vin) can not be less than one.

In order to get a gain of 2 (2 volts out/1 volt in), R2/R1 needs to be equal to 1.

If both R1 and R2 are 1kΩ, the equations reads:

Vout=(1+1000/1000)Vin

Vout=(1+1)Vin

Vout=2Vin

thanks for the info. it helps a lot.

I have a similar problem. I am trying to solve for the resistance of a resistor in series. I have been given the source voltage and the resistance of two of the three resistors. I have also been given the voltage dropped over the mystery resistor. I need to solve for total circuit current, resistance of the unknown resistor and power consumed by the circuit.

How do I solve for this problem with this many unknowns? Thanks in advance!