Teaching Electricity in Year 6 help

[badabinglad]

Hi, I am a primary school teacher in the UK and I want to try and teach an objective and I'm struggling to find the knowledge/resources that I want.

The objective I want to understand as well as teach is essentially teaching that certain materials are better conductors than others and measuring their conductivity to prove this

I want to create a basic circuit with a 3V battery, wires and a multimeter which gives me a reading. I assumed that the more wires I put into the circuit, the lower the voltage reading would be, however it is not changing, regardless of where the battery is placed in the circuit. It is also only changing extremely marginally if I add in different materials into the circuit

For example, I added in the following materials into the circuit and this is what the multimeter reading still was

Copper - 2.11V

Alluminium - 2.13V

Stainless Steel 2.11V

Mild Steel - 2.07V

Brass 2.05V

Wood - 0.00V

Is this an accurate measurement? Or have I created a test which doesn't test the actual electrical conductivity of the materials?

I also thought more wires in the circuit would reduce the voltage reading because of the resistance in the cables? Have I misunderstood something? The first time I added a wire my reading increased from 2.13v to 2.15v

Thanks in advance

 

[Sharpend]

Sorry to say you have proved nothing. 
I would suggest you look at Ohm’s law which will give you a basic understanding of the fundamental principles in the relationship between Volts, Current, Resistance. 
Once you understand this you will understand where you went wrong. 

 

[kerching]

You need long bits of thin wire to make any observable change in res.  A drum of alarm cable is useful,as it usually has 6 cores so you can connect them to give 100/200/300/400/500/600m of cable

you also need to zero your leads OR at the very least measure theirmresistance and deduct this value

in brief, and in terms that my daughter can understand as she is head of faculty,

long thin wire= hi resistance

short fat wire = low resistance

 

[Andy™]

you wont get a low enough volt drop with just that, youll need a much higher resistance, either by a very long cable or some resistors. theres a bit more to it than that though

 

[badabinglad]

Thank you for all of the quick replies. They're all extremely useful!

 

[Phoenix]

What load are you applying to the circuit?, I only see reference, to a battery, cables and a meter, and no load (lamp, bell, burden resister, etc) its worth pointing out that if there is no load you won't see any difference as the open cirucit voltage will be unaffected by the increased resistance (at least up until the point that the internal impedance of the meter, high as it is, becomes significant)

 

[kerching]

Never even considered there to be no load!  Teachers eh

Without a load all you are doing is shorting out the battery thus reducing its voltage output

 

[Sharpend]

Never even considered there to be no load!  Teachers eh

Without a load all you are doing is shorting out the battery thus reducing its voltage output

I do believe that is what the teacher concluded in their tests!! 

 

[kerching]

I do believe that is what the teacher concluded in their tests!! 

And without even knowing it

 

[binky]

I do believe that is what the teacher concluded in their tests!! 

AHH but some bits of metal short better than others. Now where is my rusty nails, I've run out of fuses.

 

[Sharpend]

And without even knowing it

Isn’t that the definition of a hidden genius??