Why is a Potential Divider Required in Sensor Circuits?

[lincsimp]

Homework Statement

Why is a potential divider required in a sensor circuit?

Homework Equations

V_out = r1/(r1+r2)*V_in

The Attempt at a Solution

Firstly you can get the required voltage across the sensor by changing the resistance of r2 (if r1 is the sensor).

Apparently, though, using a potential divider also increases the sensitivity of the sensor. ie. a small change in resistance causes a larger change in output, but I don't see how this works. could someone explain?

Thanks

 

[lincsimp]

any ideas?

 

[Mentz114]

Your answer seems logical - i.e.to get the correct voltage drop across the sensor.

You can work out the sensitivity by calculating d v_out/dr1 where r1 is the sensor resistance, as a function of r1 and r2.

 

[lincsimp]

ah thanks! a bit of calc shows that you have maximum sensitivity when r1=r2...