How many lemons does it take to make a light bulb light?

It takes at least 4 lemons to light a small light bulb.

77 and 3/4 of a pear

The acidic nature of the lemon juice creates a chemical reaction with lead or another metal inserted into it which causes current to flow in the wire hooked to a low power lamp. The lemon juice is...

Just one, but it requires someone with a modicum of intelligence to remove the old one and replace it. :)

Yes, If you had an electromagnet