How do I find the switching voltages from a relay's data sheet?

I'm doing a school project and the course so far has taught us nothing but resistors really. Some project to be made. So I'm trying to figure something out myself. I'm using a photocell to control a relay to control a motor (DPDT relay, so two-direction DC motor control based on light). My question... show more I'm doing a school project and the course so far has taught us nothing but resistors really. Some project to be made. So I'm trying to figure something out myself.
I'm using a photocell to control a relay to control a motor (DPDT relay, so two-direction DC motor control based on light). My question is:
How do I know what relay to use? I have all other stats on things, but the relays are confusing me. Specifically I have the datasheet for JW2SN-DC12V and I don't really understand it; how do I find the switching voltage (point at which it changes from one position to the other)?
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