In April I assigned various special topics for the students to investigate and report back to the class. These topics were assigned for various reasons: to become familiar with current technology, to improve writing skills, and to practice presentation skills. This needs to be done in more classes as it appears that many of the students lack these skills!
Now on to the subjects:
How do high and low temperatures impact the range of an EV (electric vehicle)? Fortunately there is some research published on this topic. As EV's become more popular potential owners need to be aware of the impact of temperature on the power of a battery, and more importantly, the impact of running the heater or air conditioner. Depending on the range of temperature and the creature comforts in use, range could decrease 10 to 20 percent!
In their comparisons to a gasoline powered car, it was evident that many students had no idea how various components of the car worked. For example, one student claimed that running the heater would also reduce efficiency but in reality heat in the passenger compartment is created by using waste heat otherwise cooled by the radiator. My Dad showed me how many systems in the car worked, but it was easier when you could see and access the radiator, battery, spark plugs, etc. He also used this education as a way to sign up my brother and me for free labor changing tires, washing and waxing, oil changes etc.!
Operating cost comparison for an electric, gas, and hybrid car. Since these students are home-schooled and typically from large families, there is more of a practical attitude and less political correctness when it comes to the economics of electric and hybrid cars. The gas powered car was significantly less expensive to operate owing to the lower purchase price, which also resulted in lower costs for financing, insurance, and property taxes. In terms of an economic break even point, they discovered that it would take at least 8 to 10 years for the EV to be cost effective; and that only works if you do not have to replace the battery! Or in the case of many Teslas, replace the door handles which cost a grand a piece. Also, as a finance guy professionally, I do not invest where there is an expected 8 or 10 year payback!
What is an Eddy Current? An Eddy Current is easy to show. Just drop a relatively strong magnet down a copper tube. The magnet creates a magnetic field parallel to the tube. These fields create a circular magnetic field above and below the magnet, perpendicular to the tube. This charge on the bottom is the same as the charge on the bottom of the magnet. These charges repel and make the magnet fall much more slowly than it would based on just the pull of gravity. We did not find many practical uses for the Eddy Current but it was fun to discuss, demonstrate, and draw pictures of the fields.
How does a Mag Lev train work? Another example of magnetic fields in use. One has to draw a detailed diagram to fully understand where the magnetic fields are placed to make the train float above the "track" Even more interesting is how a linear motor works. By switching the magnet fields on the side of the tracks back and forth the magnets attract the train as the train approaches and repel the train as it goes away. These fields can also be used to stop the train! This is a very simplified explanation so go do your own research and look at some diagrams!
How do wireless chargers work? I am not an early adaptor by any means so at this time it looks like wireless chargers are for people too lazy to plug in their phone or tablet to charge. However when the wireless charging towers are further developed so that devices can be charged as a group meets around a conference table this would end the struggle to keep a couple dozen phones, tablets, and laptops charged during a long meeting (of which I have been in attendance for quite a few in my career in business).
Everyone had a good time presenting their topics and asking many questions of those who were presenting. We are now on round three (at least) of revisions to their written reports.
Next year we are teaching Chemistry, Statistics, and Physical Science which will include participation in a science fair. We will probably therefore offer a writing workshop at the beginning of the school year for all the students. Our library has a good course online; we will probably use that as a base.
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