An impulse is a sudden force or desire — this could be an electrical impulse, or an impulse to get some pizza.
If you act on a sudden feeling or thought, you’re following an impulse. That's like a whim: an impulse isn't something you've given a lot of thought. Another meaning of impulse is an electrical charge or pulse. Electrical impulses are coursing through wires all through your house every day. Both kinds of impulses make things happen. The electrical impulse keeps the refrigerator going, and then you have an impulse to eat all the ice cream in the fridge.