Why do you experience a shock or even see a spark when you reach for a doorknob.

Answer: static electricity

Explanation:

You see, you rubbed your body either against a coat or the carpet. It send negative electrons throughout your body and once you hit metal with your hand it creates an electric shock that's called static electricity.

When you touch a doorknob, all the charge wants to leave you and go to the doorknob. You see a spark and get a shock as the electrons leave you. Lightning is the result of static electricity.