14th of May's Class
Current is passed through the wire in the image above. As current flowed through the wires, the wires repelled each other. This is because of the magnetic field they produced are identical to each other. When one of the wires had its current flowing in reverse, the two wires attracted each other.
The video above shows the reaction that was described above. However, the movement from the wires are very slight.
We were asked to predict the directional vectors of the Force and Torque. The prediction we made was done in black marker. If there is an orange marker next to the prediction we made, means that that is the correct answer, and our prediction was off.
Next, we had to do an experiment related to the number of loops a wire and its effect on magnetic field. We had forgotten to take a picture of the set up so there would be no images that shows how the experiment looked like. What we had to do was coil a wire around the outer radius of a test tube. Then using a Hall-effect meter, we measure the magnetic field within the test tube.
As the coiled wire generates a circular current, the magnetic field produced would be a straight line contained within the radius of the test tube. We were supposed to measure the reading of an increasing number of loop on the test tube (From 1 to 5 loops).
The next 5 images shows the result we got, from 1 loop to 5 loops.
While it is not readily noticeable in some of these images, there is an increase in magnitude of the magnetic field, therefore it can be deduced that the strength of the magnetic field is directly proportional to the amount of loops that the current-carrying wire is coiled into.
Next, we were given two situations of a plate and the flux it experiences. As the definition for flux is the number of magnetic field lines that the surface area could enclose, the above is the resultant calculation for each plate's orientation. As the lower plate encloses none of the magnetic field lines, its flux is therefore 0.
We were then introduced to an old piece of equipment named galvanometer. Its function is to detect current and give an analogous reading.
We could not get a the earlier demonstration due to the amount of people gathering to watch the demonstration. What happened in this demonstration is basically a loop of wire is hooked up to the galvanometer, and it showed 0 A. There was no current at this point of time.
Professor Mason then took a bar of magnet and inserted it into the center of the loop of wire. The galvanometer then jumped up for a second to give a reading of Current. Then, if he pulled it out, the galvanometer would get another reading, but this time in the negative direction. He repeated the demonstration again, but this time he inserted and pulled out the magnet at higher velocity. What happens is that the galvanometer received a higher reading of the magnitude of the current flowing within the wire.
In this demonstration, we learnt of three things: Magnetic Field can generate current wirelessly, the velocity of the magnetic field determines the magnitude of current generated, and that the direction in which the magnetic field moves determine the direction of the current generated too.
Professor Mason then quickly gave us another demonstration. The red apparatus seen at the left side of the image above is a transformer. As it generates varying voltages, the current would be passed through the coils of wire in the center of the image above. The black metal pole that is seen sticking out would then generate a magnetic field.
As we can see from the video above, the metal ring levitated. This is caused by the magnetic field ,that was generated from the metal pole, inducing a magnetic field on the ring too, but in the opposite direction. When the two magnetic fields clash, they created an equilibrium of force that allowed for the ring to push itself against gravity and its mass with enough force.
In the next video, the levitation does not occur as the metal ring was not continuous all around, therefore causing current to be unable to flow through the metal ring. With the absence of a generated current within the metal ring's body, there can be no magnetic field too. Hence, there is no magnetic field that can be used to oppose the magnetic field of the black metal pole. Therefore, it cannot levitate.
The image below describes the factors that affect the magnitude of the generated current through magnetic field:
And the next image is a diagram that describes the phenomenon that I attempted to explain before about the levitation of the metal rings.
Professor Mason then gave us another demonstration about the effects of magnetic field and its induced magnetic field. He took two objects of the identical masses, with the only difference being that one of them is magnetic and one is not. He will be putting them through two different tubes. One is made of acrylic, the other, steel.
First, he placed the magnetized mass into the acrylic tube, and the non-magnetized mass into the steel tube. He let them fall, and as predicted, both of the mass fell out of their respective tubes at the same time. Next, he placed the magnetized mass into the aluminum tube, and the non-magnetized mass into the acrylic tube. This is what happened:
Basically, the magnetized mass fell through the metal tube at a slower rate than its non-magnetized counterpart. This can be explained in a similar fashion with the levitating ring. The induced magnetic field in the metal tube causes an opposition force to the fall of the magnetized mass, causing it to travel at a slower rate down the tube.
The image above is a diagram that attempts to describe the phenomenon that just happened.
We were then given these equations:
Its significance lies in the fact that if there is no velocity (stationary) from the object, there cannot be an induced magnetic field or current.
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