Why is 100 mV the best range to be selected on an electrometer?
I am running a test using an Ussing chamber to determine membrane potentials.
I have been asked why 100 mV us a good range to use?
- ZirpLv 71 month ago
Well, that depends on what you use it for.
For the electricity that runs your household-appliances such a range would be useless
- Steve4PhysicsLv 72 months ago
Typical membrane potentials are between -40mV and -80mV. The 100mV range maximises the display precision for these values.
If that’s not clear, here’s a more detailed explanation.
Consider a 4 digit display. Ranges usually change in factors of 10. Suppose the potential is 51.23mV.
The 10mV range is too small. The display can only show values from 0 to +9.999mV or 0 to -9.999mV An ‘over-range’ symbol will be displayed is -51.23 is outside the possible range.
A range of 1000mV (=1V) will work but you lose 1 digit precision. The display will show -051.2 so you only get 1 decimal place. (The leading may be shown as a blank.)
But using the 100mV range the display is -51.23 which gives 2 decimal places.
- JazSincLv 72 months ago
Probably because some grad student or undergrad spent a summer figuring out what worked best. Check the literature for the paper(s) that were written by that "team."