In general, how can you tell?
As a specific example, how would I know from looking at the following datasheet? http://www.alps.com/products/WebObjects/catalog.woa/E/HTML/Potentiometer/RotaryPotentiometers/RK09K/RK09K1130AV7.html
In general, how can you tell?
As a specific example, how would I know from looking at the following datasheet? http://www.alps.com/products/WebObjects/catalog.woa/E/HTML/Potentiometer/RotaryPotentiometers/RK09K/RK09K1130AV7.html
The relationship between the angle of the knob and the resistance is the "taper". That datasheet says this pot's taper is "1B".
Finding information on what 1B means is a bit tricky. It's at the related information link at the top. The tapers are described at the very bottom. Here's the relevant image:
It's hard to read, but 1B is the straight line in the upper-left. This is an ordinary linear pot.
This is something of an industry convention. See for example Alpha's pot tapers. By convention, anything with a "B" in it is a linear taper. Anything with "A" in it is "audio" or "logarithmic".