Does A Lemon Battery Really Work?

Yes :) i just did mine as my sci fair project and it lit up an LED light. I used since zink coated screws, and copper bars (or for the copper you can use a penny made before 1982 or strip a wire and use that copper). You then attack the wire to all your lemons(you need around 6 to 7 lemons) do zink to copper zinc to copper. Then at the end of your row of lemons put an indival wire on 1 screw and 1 copper bar. Then connect it to the wire of the LED light    or for some night lites you can attack the wires to the metal part. P.S. Most forms of liquid or fruit or vegie can light a LED bulb.(but can goods dnt work as well) i tested it using.... 1. Lemons 2. Celery 3. Cucumbers 4. Sprite 5. Water. Also solids will not light an LED up even with copper and zink. Ex: I combined my cellery with a bowl of sugar and the LED did not light up because the sugar broke the flow of the circuit.

Sure, they produce electricity.  But they are mostly used as educational experiments and not practical for everyday use.

No

Yes ,a lemon battery work but of course it only gives a very little glow on the filament of the bulb so it could not be seen easily