Amrita Vishwa Vidyapeetham, Amritapuri Campus
Posts tagged physics
JACOB’S LADDER
Oct 22nd
JACOB’S LADDER
This is a very simple project you can build.
You will need the following:
1.) Neon transformer or a oil burner transformer (at least 5KV).
2.) Heavy-duty grounded plug/cord. Cords from computers work nicely.
3.) 8 to 12 gauge copper wire. Clothes hangers work nicely when the paint is removed.
4.) Wood for the base and frame.
I used a 12KV 60mA neon transformer, which is easily capable of making a nice white arc. The rods start at about 1/4 – 1/2 inch at the bottom and end at 2 – 3 inches on the top. Microwave oven transformers are not recommended because most provide 2.5KV at 500mA; the voltage is too low to start an arc easily and the current is rather high. I had some luck with using neon transformers at around 5KV, but starting and sustaining an arc is difficult. A 1Meg resistor has to be connected to one of the rods and the other end of the resistor is placed between the rods at the bottom to help start the arc. The rods cannot spread out over an inch with transformers below 9KV or the arc will extinguish prematurely. Below is a basic schematic diagram of the circuit.
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SIMPLE MAGLEV TRAIN
Oct 19th
| SIMPLE MAGLEV TRAIN (c)1996 W. BeatyA truely levitated maglev train is a very complex device. Permanent magnets alone cannot suspend a train car. You’d also need coils, amplifiers, and negative feedback too. I’d only recommend the coils/sensors approach if you are a college student or fairly advanced highschooler.However, there’s a way to make a simple permanent-magnet maglev train. Instead of using coils and electronics, we just put guide rails on the sides of the track. The guide rails will lightly touch your train and keep it centered. Because real science involves striking out into the unknown, I’m not going to give detailed plans here. Just enough info to get you started. The lifter-rails under your train will be small square ceramic magnets. Radio Shack stores in the US sell a good type, the 1″ x 3/4″ square with a hole in the center. Each foot of train track will require 32 of these magnets. Less expensive magnets are available from All Electronics, but I haven’t tried these (see links at end of article). First mark one pole on all of your magnets so you later can lay them down with the same pole facing upwards. To do this, stick your magnets all together in one big long stack. Now use a permanent marker to make an “X” on flat face of one end of the stack. Pull the marked magnet off the stack, make an “X” on the next one, etc., until you’re out of magnets. Mark every single one on the same side. Before building an entire huge track, make a “test bed” about one foot long. For a base, you can use cardboard or wood. Don’t use iron or steel of course. You’ll be lining up your magnets side by side in long rows. One way to do this is to stick them to a strip of duct tape, then lay the strip down on the cardboard or wood and rub the tape down to hold the magnets underneath. Position each magnet carefully on the tape so the row is very straight. Make two parallel rows of magnets with about 5cm of space between the rows. Make sure the rows are perfectly parallel. It might help to measure with a ruler and draw lines on the base first. For a temporary “car”, cut out a square of cardboard 9cm by 15cm . Tape four magnets to the corners, flipping the magnets correctly so they will repel from the tracks when the cardboard is layed down. Position the magnets on the cardboard so they will be exactly over the magnets on the track. If you place your cardboard “car” on your magnet track, you’ll find that it will twist or flip over and fall, and will not hover. But if you gently hold it by its sides, you can keep it floating in position. Does this give you ideas? What if you place one long board on each side of your track? The “car” will touch the two boards and will stop slipping sideways, but the boards will not stop the car from slipping down the track. MAGLEV TRACK, board VIEW FROM THE END board ____ ____ | | | | | | | | | | magnet magnet | | | | row row | | | | _____ _____ | | __|____|____|_____|______________|_____|____|____|__ |____________________________________________________| wood or cardboard MAGLEV TRACK, WITH FLOATING CARDBOARD CAR IN PLACE ____ (end view) ____ | | | | | | | | | | __________________________________ | | | ||__________________________________|| | | | |_____| |_____| | | | | _____ _____ | | __|____|____|_____|______________|_____|____|____|__ |____________________________________________________| |
| Once you get this part working, you can build a much longer track. You can build a real car too, one that looks like a train, although you’ll have to find very lightweight construction materials. You can try thinking up ways to reduce the friction with the side rails. Maybe try aluminum angle strips instead of wood, or sand the wood smooth and paint it with something hard and shiny.But how can you drive your train forward? I don’t know. You’ll have to think of something. There are only two ways to move a hovering object. One is to grab something on the ground and pull or push forwards (this includes tilting the rail to become a ramp; using gravity to pull the car forwards.) The other way is to force something out the back, which drives the car forward. Use the car to launch marbles rolling down a tiny ramp? Use a propellor? Squirt water? Rocket engine? |
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