Motor experiments: mono pole motor , electric mole, permanent sesame
Use Fleming's Law to create different motors. As a further development, we will produce permanent spinning top.
Experiment 1: Let's make the simplest mono pole motor
you need : neodymium magnets, nails, copper wire
Prepare the ingredients. Attach a neodymium magnet to a nail and connect it to a dry battery. Stick the copper wire to the opposite pole of the battery and touch the neodymium magnet. The magnet starts to rotate. It is a motor with the simplest structure. However, since the battery is short-circuited, a lot of current flows. The copper wire also gets hot, so make it a short experiment.
Principle of rotation: A copper wire causes an electric current to flow and creates a magnetic field around the copper wire. The second figure is seen from above. Neodymium magnets also magnetize the battery and emit magnetic force lines as shown in the third figure. If you overlay this on the top view, you will see the fourth figure. When viewed from above the copper wire, the magnetic fields cancel each other out and become sparse in the right direction, so the force acts in this direction. The movement of the unipolar motor is like this. It is a little difficult because it requires a three-dimensional effect.
Experiment 2: Let's make a mono pole motor ②
you need : Ferrite magnet, enamel wire, aluminum foil, sandpaper
Prepare the materials. Make a ring with enamel wire. Use sandpaper to remove the enamel from the upper pointed part and the lower ring part.
Wrap aluminum foil around the ferrite magnet. Attach a frame to the + pole of the battery with a straw. Pay attention to the balance and it's done.
Experiment 3: Let's make an electric mole. mono pole motor ③
you need : Copper wire, AAA batteries, washers (non-magnetized) or paper rings, neodymium magnets 4
Make a tunnel with bare copper wire. Instead of winding the copper wire around the rod, you can do it well by rotating the rod and winding the copper wire. A magnet is attached to the battery, but a washer is sandwiched between the protrusions of the + pole to stabilize it. Neodymium magnets always sandwich the battery so that the same pole is on the inside. After that, insert a copper wire and it will move. Think about the principle of operation.
Experiment 4: Let's make permanent spinning top
you need : Donut type ferrite magnet (single-sided NS), nail, enamel wire, reed switch, LED, container
Stick a bamboo skewer into the magnet to make a piece. Wind the enamel wire around the nail about 100 times to make a coil. Connect the LED and the reed switch in parallel. Connect the 1.5V power supply, LED, and coil in series. Use a container with a concave bottom, such as a pudding cup. Stick the LED and coil on the bottom. After that, adjust the position so that the LED blinks when you turn the piece. done.
Principle of operation: The reed switch repeats on and off as the top rotates. When turned on, current flows and a weak magnetic field is created in the coil. Since it is 1.5V, the LED does not turn on, of course. The coil current stops flowing the moment it is turned off by the rotation of the top. At this time, it is called back electromotive force and tries to cancel the change. This voltage applies force to the frame and continues to rotate. Please see the PDF below for details.