7th of May's Class
This is a horseshoe magnet that was brought out to us at the beginning of the class. It was used to magnetize a paper clip that was placed on top of it. The paper clip cannot be seen clearly due to the poor resolution of the image. It is therefore marked with a red circle above.
The demonstration serves a purpose to inform us that the magnetic force causes a shift in the positioning of the positive and negative charges present within the paper clip. The polarity of the charges causes the paper clip to be able to generate a magnetic field of its own.
Professor also informed us that when the paper clip is cut in half, the cut paper clips would have different magnetic poles. If it was to be cut into really small pieces though, the magnetism would disappear.
The image above is a picture of when Professor Mason demonstrate to us the effect of the magnetic field that the paper clip obtained from the horseshoe magnet. It affected the small compass on the table, indicating the pole that it was magnetized with.
Flux in magnetism is defined as the number of poles that is enclosed within a particular circle. It's formula is defined by N (Number of poles enclosed) divided by Epsilon. The flux of a magnetic field is always equal to 0. The common unit used for measurement of magnetic field is Tesla. Though in common uses, the unit Gauss, which is 1/1000 of Tesla, is much more practical.
Next is a video showing the effect magnetic field has on an electron. For visual convenience, the oscilloscope is used as an apparatus that aids us to view the movement of an electron under the influence of magnetic field.
The movement of the electron is dependent on the orientation of the magnetic field. The image below describes Professor Mason's demonstration. Circled in red is the orientation of the magnetic field for the first run. The magnet is brought closer to the oscilloscope from the top, first with the North end of the magnet, then with the South. The resulting phenomenon was recorded right below. The direction that the electron moved is marked with the F vector in each diagram.
Professor Mason then asked us to predict the movement of the electron if the magnet were to approach the oscilloscope from the side. Our prediction is circled in yellow. With this, we were brought to the attention that their movements mimic the right and left hand rule by Professor Mason. He then further informed us that the right-hand rule determines the direction of protons, while the electrons' movements are predicted by the left hand rule.
Next, we attempted to figure out the unit of measurement for magnetic field. Since it is defined by Force divided by Charge and Velocity, the resulting unit is kg/(c*s) or N/(Am).
We were then asked the question above as a practice for our magnetic field calculation. Our working and calculation is shown in the image below. We would first determine the direction of each vector, and then calculate accordingly.
As it turns out, electrons do not just move in a straight line when under the influence of a magnetic field. There is a rotational movement involved as well, and depending on the charge, the orientation of the rotation would differ. This is shown in the image below. The upper half of the white board in the image below is the equation needed to define radius of the rotation.
Professor Mason then gave us a practice question that relates the magnetic field with something that is more familiar and tangible, the frequency of waves. The question goes like this:
The formula we used to bridge magnetic field and frequency is angular velocity. With some substitution, we can derive the magnetic field needed to make the electrons move in circular paths, for that frequency in particular.
The next demonstration involves the horseshoe magnet again, by placing a metal wire right in between it, we are causing a magnetic field to pass through it from the north to the south pole of the magnet. We are then to observe the reaction the electrons present within the wire would have when it is under the influence of the magnetic field as current flows through it. The current will be supplied to the wire by the camo green apparatus in the background.
The magnetic field is moving from the wire's left to right side (from this perspective) and the current is moving to the background, hence it creates a vector that goes downward for the electrons to move. With this, we can deduce that a charged wire moves like a charged particle.
The demonstration then continued with a slight change to the set up, instead of a straight wire being placed within the horseshoe magnet, it was a metal wire in the shape of a loop. We were supposed to predict what is going to happen from these choices:
a) Spin continuously in counterclockwise direction
b) Spin continuously in clockwise direction
c) Spin upwards 90 degrees
d) Spin upwards 180 degrees
e) None of the above
This is what happened:
The image above is the explanation given for the phenomenon that occur in the video. The metal loop simply assimilated the position where it is most stable. The position is depicted on the left side of the white board.
Professor Mason then gave us a hypothetical question with a semi-circle metal wire that is under a magnetic field going upwards. We were supposed to predict the direction the electrons would move, and our prediction is that from this perspective, the movement of the electron would be to move in the z-axis, out towards the viewer.
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