Force of a 12V push-pull electromagnet switch

[Darwinian]

I'm making a 'Stay out of my room you bloody cats' device.  I already have a motion sensor that I modified but at the moment it's rigged up to a couple of hair dryers that blast air at them, and they are getting a bit blasé about that. It's also very noisy.

With the electromagnet I can rig up something that will spay some air freshener in their direction once they cross the threshold.  They really hate air freshener and I doubt they will ever get used to it.

I've told them. All these rooms are yours except mine, attempt no incursion there.  But they don't listen.

You will never be able to twart my minions of purring cats.

It's a battle of wills And I shall prevail