Thread: Lemon Battery Problems

I'm doing an investigation at school involving lemon batteries, and today's pre-trials were a disaster. I couldn't get a reading from the lemon battery using a Voltmeter, Microammeter and Multimeter (electronic ammenter and voltmeter). I also need to substitute the lemon for a lime, grapefruit and orange, and if I can only get a small reading from the lemon then I will be lucky to get any reading from the other fruits.

I'm fairly sure I did everything right, so this baffles me. Can anybody offer some help?

1. What did you use for electrodes?

2. How far apart were they separated?

3. Did you verify that your meter works?

When you measure voltage the multimeter is in parallel. To measure current it's in series.

Make sure you have the dial on the multimeter set to the correct magnitude.

Originally Posted by Geo

When you measure voltage the multimeter is in parallel. To measure current it's in series.

In series with what? Sam hasn't mentioned any load yet. He's struggling to get any indication of electric activity from his battery. I understand he's connecting each meter in turn directly to the electrodes - in a way that, for a more powerful "real" battery, would ruin the microammeter, but which _may_ be right for a very weak power source.

Originally Posted by jrmonroe

1. What did you use for electrodes?

2. How far apart were they separated?

3. Did you verify that your meter works?

1. Zinc and copper.

2. A few centimetres - I'm sure that they weren't touching, and from diagrams that I've seen they shouldn't have been too close together.

3. No. I did get a reading from the multimeter, but if I remembered correctly then it was something like 0.8, and that was measured in 1/200 of a volt. I've done my research, and for the lemon to be producing such a feeble amount of electricity is puzzling.

If "0.8" means 0.8 volts, then this sounds reasonable.

0.8 volts is spot on. I'd be impressed if you get much more than that.

Try having a look at the 'bagdad battery'. Google it or on wikipedia. Used by the egyptians 2000 years BC. discovered in Irac. Jar with copper tube with an iron core gave out 1/2 volt when lemon juice used.

Originally Posted by TarquinTaylor

Try having a look at the 'bagdad battery'. Google it or on wikipedia. Used by the egyptians 2000 years BC. discovered in Irac. Jar with copper tube with an iron core gave out 1/2 volt when lemon juice used.

It is very doubtful that the "bagdad battery" was actually a battery. See the wikipedia page for why, I don't particularly feel like copy and pasting it.