Science Buddies: "Ask an Expert"

Can somebody tell me why Vegetables+fruits can conduct electricity?

What grade are you in and what do you need help with?

I'm in fith grade and I'm not so sure how can fruits and vegetables provide electricity.By the way is it likely that apples can give enough electricity?

Have you read this? https://www.sciencebuddies.org/mentorin ... ?from=Home

Can somebody tell me why Vegetables+fruits can conduct electricity?

A "conductor" of electricity is something that will allow electrons (electricity) to move freely from one place to another.

Water is a "conductor". Salt water is an even better "conductor". Fruit and vegetable juice contain water (so they conduct). The juice also contains other chemicals which usually make them better conductors than distilled water.

I'm not so sure how can fruits and vegetables provide electricity

This is a different question than your first. Most fruits and vegetables contain various chemicals (weak or dilute acids and water soluble salts and minerals). These chemicals in the juice will chemically react differently with the two different metal electrodes. The chemical reactions at the "anode" metal causes it to give up electrons to the juice.
The reactions at the "cathode" metal causes it to collect electrons from the juice. The anode then has a positive charge because it is missing electrons. The cathode has a negative charge because it has extra electrons. This effect can be measured with a digital volt meter.

The words I've used to explain this are probably new to you. Find a good dictionary and look them up. The dictionary meanings should help your understanding. If not, ask about a specific word and somebody here will try to find a reference that explains it or will try to explain it so you can understand it better.

By the way is it likely that apples can give enough electricity?

How many apples and enough electricity to do what?

This sounds like the type of question you can find the answer to experimentally. Your the "investigator"!

Do some searches to find out about electrical units and Ohm's Law and DC power equation. "V = I x R" and "P = V x I" might give you a hit. Look at the electrical ratings on some battery powered equipment you own. The Project Idea URL I cited earler has some thoughts about what you might try.

for the question about apples, I did the experiment and the experiment worked with the apples. It only takes 3 apples to make the calculater to work. I'd just like to know that does apples work as a conductor if I used it.

99help wrote:for the question about apples, I did the experiment and the experiment worked with the apples. It only takes 3 apples to make the calculater to work. I'd just like to know that does apples work as a conductor if I used it.

Read Craig's post again. There is a difference between a conductor and a battery. You are using the apple and the metal to make a battery to _generate_ electricity.



Louise

You have me confused.

I did the experiment and the experiment worked with the apples. It only takes 3 apples to make the calculater to work.

I read this to mean that you made a 3 cell battery hooked in series and powered a calculator.

I'd just like to know that does apples work as a conductor if I used it.

Are you asking about using apples in place of copper wire as a conductor? Are you asking about ion conduction that was happening inside the apples in your experiment? I don't know what you are really trying to ask.

I'm asking about the copper wire and the iron nail. And I would like to know what's happening inside.

99help wrote:I'm asking about the copper wire and the iron nail. And I would like to know what's happening inside.

This is a battery.

Look at what was posted before:

Craig_Bridge wrote: This is a different question than your first. Most fruits and vegetables contain various chemicals (weak or dilute acids and water soluble salts and minerals). These chemicals in the juice will chemically react differently with the two different metal electrodes. The chemical reactions at the "anode" metal causes it to give up electrons to the juice.
The reactions at the "cathode" metal causes it to collect electrons from the juice. The anode then has a positive charge because it is missing electrons. The cathode has a negative charge because it has extra electrons. This effect can be measured with a digital volt meter.

This is what is happening. If you don't understand these terms, you should look them up. In the project description there are many useful links.
https://www.sciencebuddies.org/mentorin ... ?from=Home

You can also search for "how batteries work" on the web.


Louise

You need to look up some words and do some reading Louise suggested! Part of science is the communication of ideas. Scientific ideas require a bigger vocabulary (understanding more words and alternate meanings and using them properly).

Now that I understand what you are asking about, I'll give you another hint.

The bare copper wire and the nail are both metals. Metals are electrical conductors, but they can also become involved in chemical reactions.

The surface of the dissimilar metals that are exposed to the apple are no longer simply electrical conductors. Their surfaces in the apple juice (electrolyte) are now electrodes (anodes and cathodes) and are undergoing chemical reactions.

If you are thinking that just placing electrical conductors into an apple will magically extract an electrical current, then try the experiment again just using copper wire electrodes and see what happens.

Another part of scientific understanding is also doing variations on experiments to and see differences to really understand the original experiment.

Craig_Bridge,

So if fruits and vegetables can conduct eletricity, then is it a matter of of amount of elctroides inside the fruit or vegetable that can produce the amount of electricity?

99help wrote:Craig_Bridge,

So if fruits and vegetables can conduct eletricity, then is it a matter of of amount of elctroides inside the fruit or vegetable that can produce the amount of electricity?

It has to do with the chemical reaction between the electrodes and the fruit. It related to the "amount of electrode" only that if you have more area you can do more chemical reactions.

See this page at the wikipedia for more information about the chemical reactions:
http://en.wikipedia.org/wiki/Lemon_battery

Louise

Please read the reference Louise gave you.

With electricity, there is always more than one "amount" or measurement involved. As a minimum, there are at least two. Everybody starts out confused by this need for two measurements.

"Amount" of electricity produced by a battery
There are several electrical quantities involved in battery (direct current) circuits.

1) The open circuit (little or no current flowing) "voltage" (measured in volts) produced by a battery cell is determined by which metals are used as electrodes. Look up "galvanic series" http://en.wikipedia.org/wiki/Standard_e ... ta_page%29 The difference between the the two entries in this table for the two metals used predicts the open circuit voltage.

2) The short circuit current (maximum current) produced by a battery cell (typically measured in milli-amps for small batteries) is determined by the electrode surface area in contact with the electrolyte and the internal resistance of the "salt bridge" between the electrodes. This is the measurement that Louise was referring to and is limited by the chemical reaction rates.

3) The power delivered to the load (calculator in your experiment) at any point in time is the voltage multiplied by the current (volts times milli-amps = milli-watts).

4) The total energy available from a small battery is usually expressed in milli-watt hours which is how much power for how long that the battery can supply. When the anode is fully oxidized or the cathode is fully reduced or the electroyle is exhausted (whichever comes first), the battery will no longer produce current.