Teaching Boy Scouts

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jimmy_mcquade

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Hi Everyone,

I am working with the boyscouts and one of the things they have to do is earn merit badges. The merit badge i have been asked to teach is electricity.

The hands on stuff is with dc batteries so no biggie.
One of the things i have to explain is what is amps and volts. Rather than
the technical definition, does any one have a simple explination that the scouts can relate to?

thanks in advance.
Jimmy.

Thanks Mike for the great website.
 
I once develolped a training session on the basics of electricity. So yes, I have a great explanation of both voltage and current. And it's not just the "water pump and water flow analogy" either, it is an accurate description of the physical phenomena. That's the good news. The bad news is that I know how to explain them, but I have never written the explanation down on paper. So I don't have anything I could email you. What is your time frame? I can't promise anything. But this is something I think would be good to have handy, so perhaps it would be a good exercise for me to write it up.
 
charlie b said:
I once develolped a training session on the basics of electricity. So yes, I have a great explanation of both voltage and current. And it's not just the "water pump and water flow analogy" either, it is an accurate description of the physical phenomena. That's the good news. The bad news is that I know how to explain them, but I have never written the explanation down on paper. So I don't have anything I could email you. What is your time frame? I can't promise anything. But this is something I think would be good to have handy, so perhaps it would be a good exercise for me to write it up.
Click to expand...

Thanx for volunteering Charlie
 
I'll see what I can do. But again, no promises.

The water analogy equates a pump with a voltage source. Water pressure is said to be analogous to voltage, and water flow rate is said to be analogous with current. Since it is generally easier to envision something that you can actually see and feel, this analogy has some merit. It also has some pitfalls, in that there are aspects of water flow that do not behave the same way that current behaves.
 
E = I R is equivalent to F = m a

Force to push a car = Mass of the car * Acceleration

imprecisely: Pushing = Weight * Speed

For a given resistance (the mass/weight of the car), the more voltage (pushing) to get the same Amperage (speed/acceleration).
 
pfalcon said:
E = I R is equivalent to F = m a

Force to push a car = Mass of the car * Acceleration

imprecisely: Pushing = Weight * Speed

For a given resistance (the mass/weight of the car), the more voltage (pushing) to get the same Amperage (speed/acceleration).
Click to expand...

I like it. The analogy I tend to use often is traffic in general, your example works with it well.

Ampacity = Weight rating or width of roadway.
Ampere = Vehicle / per time.
Battery = Parking garage.
Capacitor = Rest area.
Change in amplitude = Acceleration or deceleration.
Conductor = Lane.
Conductors, paralleled = Multiple-lanes.
Conductor, 'return' = Opposing lane.
and so on.

Analogies aren't reality, they all break down at certain points. If you like this idea I can post the rest of my list.
 
Not sure how deep or accurate your looking for; but
Amps do the work and slide on the volts which is like grease.
To do more work you need more amps, to get the amps to where the work is needed you need more grease(volts).
Too little grease and friction builds up on the wire and creates heat.
Too much heat and the breaker trips.
 
sameguy said:
Not sure how deep or accurate your looking for; but
Amps do the work and slide on the volts which is like grease.
To do more work you need more amps, to get the amps to where the work is needed you need more grease(volts).
Too little grease and friction builds up on the wire and creates heat.
Too much heat and the breaker trips.
Click to expand...

Upsy - Downsy

Volts do the work.
Resistance is a lack of grease.
Amperage is how fast you work.
 
one 120W 120V lamp= 1A
two 120W 120V lamp=2A
volts= force applied (to move electrons)
Amps= quantity of electrons
Resistance= opposition to the flow of electrons
When he hooks up his lamps and the voltage remains the same when lamps are added the amp meter keeps going up how is he going to get the idea across to kids? Boy scouts are what 12yrs. old and up.
 
Volta said:
I like it. The analogy I tend to use often is traffic in general, your example works with it well.

Ampacity = Weight rating or width of roadway.
Ampere = Vehicle / per time.
Battery = Parking garage.
Capacitor = Rest area.
Change in amplitude = Acceleration or deceleration.
Conductor = Lane.
Conductors, paralleled = Multiple-lanes.
Conductor, 'return' = Opposing lane.
and so on.

Analogies aren't reality, they all break down at certain points. If you like this idea I can post the rest of my list.
Click to expand...

I used a similar analogy when I taught amateur radio to a group of kids. Instead of cars, I used the kids!

One kid passing a point (a chair in my case) each second was an ampere.

A line of kids standing still was a conductor. When someone pushed the line of kids (voltage or pressure) the kids (or Coloumbs as it were) passed the chair. Resistance was easy, all I had to do was impede (key word) the line of kids from passing the chair. The more impedance I induced (I know, bad pun), the more pressure had to be applied to maintain the same amount of kids per second passing the chair. The analogy can be taken even further by 'widening the lanes' so to speak to allow for more than one kid at a time to pass the chair at any given second.
 
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sameguy said:
one 120W 120V lamp= 1A
two 120W 120V lamp=2A
volts= force applied (to move electrons)
Amps= quantity of electrons
Resistance= opposition to the flow of electrons
When he hooks up his lamps and the voltage remains the same when lamps are added the amp meter keeps going up how is he going to get the idea across to kids? Boy scouts are what 12yrs. old and up.
Click to expand...

It's like a room full of boy scouts trying to push small chairs across the room. The load is too small for more than one boy at a time to effectively push. So - 1 boy (120V) by 1 chair (load or lamp) moves across the floor makes 1 Amp. The voltage source can provide twenty boys to push twenty chairs across the room. Each boy is still the same amount of force (120V), each chair is still the same load, but now you can have twenty chairs moving or 20 Amps. When we exceed the voltage supply of 20 boys then they have to push more than one chair and the load goes dim, the pushing slows down, but there is still 20 Amps. At that point each chair is being supplied by less than 1 boy (<120V).
 
OK, Jimmy, I have something I could send you. But I don't think I should post it here, not just yeat anyway. It is not "refined," and may have typos or discontinuities in the explanations, since I did not have the kind of time I would like to have, in order to create a smooth and coherent document. But if you send me a PM with your email address, I will let you see it in its present form. It goes on for seven pages, and is close to 4000 words.

It was written in Microsoft 2007 Word format. Is that something you can read, or do I need to save it in an earlier Word format?

Do let me know if it winds up being useful. Any suggestions would be welcome.
 
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