Homopolar Motor - Revision history

imported>Stwikiadmin: /* Additional Information */

2016-05-19T17:12:32Z

Additional Information

← Older revision		Revision as of 17:12, 19 May 2016
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	== Additional Information ==		== Additional Information ==

	* This demonstration pairs well with the ''Do it Yourself Electromagnet''		* This demonstration pairs well with the [[Do it Yourself Electromagnet]]

imported>Stwikiadmin: /* Additional Information */

2016-05-19T17:12:17Z

Additional Information

← Older revision		Revision as of 17:12, 19 May 2016
Line 80:		Line 80:
	== Additional Information ==		== Additional Information ==

	*		* This demonstration pairs well with the ''Do it Yourself Electromagnet''

imported>Stwikiadmin: /* Why This Works */

2016-05-19T17:11:31Z

Why This Works

← Older revision		Revision as of 17:11, 19 May 2016
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	===Short Explanation===		===Short Explanation===
	This is a simple motor, known as a ''homopolar motor''. A homopolar motor creates movement by having a lot of ~~moving~~ ''current''. Our battery has charge built in the positive end, and the charge wants to move to the negative end. When we connect the ends with the wire, the charge is able to start moving through it, and will do so really fast! This ~~moving charge is what we call the~~ ''current'', ~~and~~ because there is a lot of moving charge ~~it is generating~~ an electromagnetic force. This electromagnetic force is really strong, and starts to push the wire around the magnet, resulting in the spinning wire we see!		This is a simple motor, known as a ''homopolar motor''. A homopolar motor creates movement by having a lot of ''current'', or moving electrons. Our battery has charge built in the positive end, and the charge wants to move to the negative end. When we connect the ends with the wire, the charge is able to start moving through it, and will do so really fast! This ''current'', because there is a lot of moving charge, can also generate an electromagnetic force. This electromagnetic force is really strong, and starts to push the wire around the magnet, resulting in the spinning wire we see!

	The battery runs out pretty quickly, and the wire will stop spinning after a minute. If we used a rechargeable battery for this, then we could recharge the battery by manually spinning the wire counter-clockwise! However, we would have to ''manually'' spin it, and that would take a really long time. You might think that we could just set the system up the other way, with the magnet on the negative side and the wire on the positive side, and that we could get the battery to recharge itself. Unfortunately, that is not the case. The moving charge lost a lot of energy in making the wire spin, so we would have to put energy into the system in order for it to go in reverse. Not only that, but when a battery discharges, it means that both sides of the battery are now equal in charge, rather than one side having all the charge and the other having no charge. Since there isn't a charge difference, there won't be any current.		The battery runs out pretty quickly, and the wire will stop spinning after a minute. If we used a rechargeable battery for this, then we could recharge the battery by manually spinning the wire counter-clockwise! However, we would have to ''manually'' spin it, and that would take a really long time. You might think that we could just set the system up the other way, with the magnet on the negative side and the wire on the positive side, and that we could get the battery to recharge itself. Unfortunately, that is not the case. The moving charge lost a lot of energy in making the wire spin, so we would have to put energy into the system in order for it to go in reverse. Not only that, but when a battery discharges, it means that both sides of the battery are now equal in charge, rather than one side having all the charge and the other having no charge. Since there isn't a charge difference, there won't be any current.

	===Full Explanation===		===Full Explanation===
	~~'''''COMING SOON'''''~~

	{\| class="wikitable" style="color:black; background-color:#ddd; text-align: ~~center~~; margin: auto"		A homopolar motor is a simple motor that uses a large current to generate mechanical movement. ''Current'' is a flow of charge, namely electrons, and is measured in ''amperes'' or amps. Typical AA Batteries are designed to give between 1000 and 1500 mAh, or "milli-amp hours", meaning they can provide a steady 1 amp current for 1 to 1.5 hours. However, if you increase the amperage needed, then the lifetime of the battery will reduce with it. Our homopolar motor draws a lot of current in order to get spinning and to stay spinning, which heats the system up as well. This happens because of what is called the ''Joule-Lenz Law'', or resistive heating:
			{\| class="wikitable" style="color:black; background-color:#ddd; text-align: left; margin-right: auto"
			\|+ Joule-Lenz Law
			\| '''''Q''''' '''∝''' '''''I<sup>2</sup>''''' * '''''R'''''
			\|-
			\| '''''Q''''' = Heat Energy: Energy lost to resistive heating
			\|-
			\| '''∝''' = Proportional To
			\|-
			\| '''''I''''' = Current: How much charge is flowing in the system
			\|-
			\| '''''R''''' = Resistance: How hard it is for charge to flow in the system.
			\|}

			Copper wire has low resistance, but since there is still some resistance the wire will start to heat up. Metal conductors become ''more'' resistant to charge as they heat up, so the wire will get hotter the longer the motor runs. This means that the amount of current given has to ''also'' increase the longer the battery runs! This self-destructive cycle results in the battery depleting itself in a very short amount of time, which is why homopolar motors are not commonly used.

			After depleting the battery, if you used a rechargeable battery, you could recharge it partially by manually rotating the wire counterclockwise. However, we would not be able to simply set the system up in reverse and have it recharge itself. The reason for this is because the discharged end of the battery does not naturally attract the charge back to itself. If that was the case, then the battery wouldn't discharge at all! Instead, you have to provide some additional energy to the system in order to have a current flow in the reverse direction. The common way that this is done is with most phone chargers, which use a constant ''direct current'' (DC) to recharge the battery directly. Other ways that this can be done is like with a AA battery charger, which uses DC to create a reverse-current for the battery that will recharge it fully, and resupply the energy lost to heat.

			----

			This demonstration is also a great way to become familiar with the ''Left Hand Rule'' and the ''Right Hand Rule''. These rules are handy<!--PUN PUN PUN PUN PUN PUN PUN PUN PUN PUN PUN PUN PUN PUN PUN PUN PUN PUN--> ways to remember how the electromagnetic field being generated by the current is applying a force on the system. With either of the hand rules, you do the same steps: You point your thumb along the length of the wire, tracing the direction of the flow of current. You then point your index finger straight out, and curl the other fingers. Your fingers are now representing the following:

			{\| class="wikitable" style="color:black; background-color:#ddd; text-align: left; margin-right: auto"
	\| '''Left Hand Rule:'''		\| '''Left Hand Rule:'''
	\| '''Right Hand Rule:'''		\| '''Right Hand Rule:'''

imported>Stwikiadmin at 14:33, 13 April 2016

2016-04-13T14:33:48Z

← Older revision		Revision as of 14:33, 13 April 2016
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	{\| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right"		{\| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right"
	\| [[Engineering]]:		\| [[Engineering]]:
	\| Simple Motors		\| Simple Motors, Hand Rules, Current
	\|-		\|-
	\| Grade Range:		\| Grade Range:
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	\|}		\|}

	This ~~space~~ is ~~intended~~ to ~~describe the~~ demonstration ~~that is here. Please use this space~~ to ~~describe in short the demonstration~~, ~~making sure~~ to ~~mention here if~~ it ~~will require any additional safety equipment or how easily it can be adjusted for varied grade levels.~~		This simple motor is easy for students to make and fairly inexpensive. This demonstration can relate to a large variety of topics, so there are plenty of options to you on when to include it in a lesson. Be aware that the system will warm up when running, so let it cool down before handling it.
	~~Use this page as~~ a ~~base layout for editing the wiki~~. ~~Feel free to copy~~ the ~~layout onto other pages~~, ~~and to put the content as needed into the page~~.

	== Materials ==		== Materials ==
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	== Safety Precautions ==		== Safety Precautions ==

	Please read the ~~____~~ section of the [[Demonstration Safety]] page before performing this demonstration.		Please read the General Safety section of the [[Demonstration Safety]] page before performing this demonstration.

	~~This demonstration requires:~~


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	# ~~Steps~~ for the demonstration.		# Provide each student group with a battery, a foot if wire and a magnet. Have them place the magnet on the positive end of the battery and stand it on the magnet.
	~~# Be sure~~ to ~~clarify~~ on ~~steps about any safety equipment needed~~.		# Have students bend their wires for the demonstration. They should make a point in the middle of the wire to stand on top of the battery, and have the two ends of the wire bend down and inward towards the battery. Have them bend the two tips in so they can both be touching the magnet at the same time.
	# ~~Make sure steps can be understood by a first~~-~~time reader~~.		# Once they have it set up, have them try to spin the wire counter-clockwise, then clockwise. When they spin the wire clockwise, it should start to spin on its own really fast!


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	===Short Explanation===		===Short Explanation===
	This is ~~where you would provide~~ a ~~basic~~, ~~easy-~~to~~-understand explanation~~ of the ~~demonstration~~. ~~Try not~~ to ~~use too much "Science Jargon"~~, and ~~if needed add any explanation tips~~, ~~like comparing~~ the ~~demo~~ to ~~something kids~~ are ~~familiar with~~.		This is a simple motor, known as a ''homopolar motor''. A homopolar motor creates movement by having a lot of moving ''current''. Our battery has charge built in the positive end, and the charge wants to move to the negative end. When we connect the ends with the wire, the charge is able to start moving through it, and will do so really fast! This moving charge is what we call the ''current'', and because there is a lot of moving charge it is generating an electromagnetic force. This electromagnetic force is really strong, and starts to push the wire around the magnet, resulting in the spinning wire we see!

			The battery runs out pretty quickly, and the wire will stop spinning after a minute. If we used a rechargeable battery for this, then we could recharge the battery by manually spinning the wire counter-clockwise! However, we would have to ''manually'' spin it, and that would take a really long time. You might think that we could just set the system up the other way, with the magnet on the negative side and the wire on the positive side, and that we could get the battery to recharge itself. Unfortunately, that is not the case. The moving charge lost a lot of energy in making the wire spin, so we would have to put energy into the system in order for it to go in reverse. Not only that, but when a battery discharges, it means that both sides of the battery are now equal in charge, rather than one side having all the charge and the other having no charge. Since there isn't a charge difference, there won't be any current.

	===Full Explanation===		===Full Explanation===
	This is where you will explain the demonstration in full, and provide all additional information that pertains to the demo. Unlike the short explanation above, this should be worded so someone who is familiar with the topics might understand it. If needed, you can provide equations and citations for additional sources of information on the topic. This is also where you will find some answers for trickier questions, such as "How does a plane fly upside-down?" for the Bernoulli'~~s Principle demo. If you want to add a floating box for equations, copy the following:~~		'''''COMING SOON'''''

	{\| class="wikitable" style="color:black; background-color:#ddd; text-align: center; margin: auto"		{\| class="wikitable" style="color:black; background-color:#ddd; text-align: center; margin: auto"
	\| ~~This will give you~~		\| '''Left Hand Rule:'''
	\| ~~a floating box.~~		\| '''Right Hand Rule:'''
	\|-		\|-
	\| ~~The box will be~~		\| Thumb: Current
	\| ~~centered for you.~~		\| Thumb: Current
			\|-
			\| Index: Magnetic Field Direction
			\| Index: Magnetic Force Direction
			\|-
			\| Curl: Magnetic Force Movement
			\| Curl: Magnetic Field Movement
	\|}		\|}

			By using the Right-Hand Rule, we can see how the magnetic field lines move counter-clockwise around the motor while the electromagnetic force is in the direction of the battery and magnet setup. By using the Left-Hand Rule, we can see that the electromagnetic force moves the wire clockwise around the motor while the magnetic field points towards the battery and magnet.

	== Additional Information ==		== Additional Information ==

	* ~~Any extra tidbits that do not fit into other sections~~		*
	* This demonstration is a part of the (insert [[Stage Show]] here)

imported>Stwikiadmin: Created page with "{| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right" | Engineering: | Simple Motors |- | Grade Range: | Elementary School, [[Mi..."

2016-04-11T17:48:47Z

Created page with "{| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right" | Engineering: | Simple Motors |- | Grade Range: | Elementary School, [[Mi..."

New page

{| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right"
| [[Engineering]]:
| Simple Motors
|-
| Grade Range:
| [[Elementary School]], [[Middle School]], [[High School]]
|-
| Format:
| [[Hands-on]]
|}

This space is intended to describe the demonstration that is here. Please use this space to describe in short the demonstration, making sure to mention here if it will require any additional safety equipment or how easily it can be adjusted for varied grade levels.
Use this page as a base layout for editing the wiki. Feel free to copy the layout onto other pages, and to put the content as needed into the page.

== Materials ==

* AA Batteries
* Neodymium Magnets (small)
* Non-Insulated Wire

== Safety Precautions ==

Please read the ____ section of the [[Demonstration Safety]] page before performing this demonstration.

This demonstration requires:

== Demonstration ==

# Steps for the demonstration.
# Be sure to clarify on steps about any safety equipment needed.
# Make sure steps can be understood by a first-time reader.

== Why This Works ==

===Short Explanation===
This is where you would provide a basic, easy-to-understand explanation of the demonstration. Try not to use too much "Science Jargon", and if needed add any explanation tips, like comparing the demo to something kids are familiar with.

===Full Explanation===
This is where you will explain the demonstration in full, and provide all additional information that pertains to the demo. Unlike the short explanation above, this should be worded so someone who is familiar with the topics might understand it. If needed, you can provide equations and citations for additional sources of information on the topic. This is also where you will find some answers for trickier questions, such as "How does a plane fly upside-down?" for the Bernoulli's Principle demo. If you want to add a floating box for equations, copy the following:

{| class="wikitable" style="color:black; background-color:#ddd; text-align: center; margin: auto"
| This will give you
| a floating box.
|-
| The box will be
| centered for you.
|}

== Additional Information ==

* Any extra tidbits that do not fit into other sections
* This demonstration is a part of the (insert [[Stage Show]] here)