# RC filtering circuits

Heya! I've got a lab practical tomorrow to do with RC circuits, what do the terminals at the top and bottom of a filter circuit diagram mean, I'm assuming Vin and Vout is the voltage in and then 0V/ground, but what do the bottom two terminals correspond to?

Cheers

The bottom left and right are the return only. $V_{in}\;$ is input voltage across the left two terminals from the top terminal to the bottom terminal on the left. $V_{out}\;$ is the output voltage across the right two terminals from the top terminal to the bottom terminal on the right.