At the beginning of the class, the professor gives us a bar magnet and a samll compass. Then we put the compass around the magnet and observe the change of the compass and draw the picture in the photo.
we find that all arrows are leave from north pole and direct to south pole.
in this photo, we make all arrows together and draw a graph.
in this photo, the professor put iron filings sprinkled around the magnet and we observe that there are circles from north pole to south pole
in this photo, we draw three circles, one includes one of poles, another includes both of poles and the last one does not include any pole. and we should find how many arrows in and out the circles. and What we find is at the bottom of the photo.
Then the professor shows us a large magnet and put a iron wire on it. and when we take the wire to close to a compass and we find that the arrow in compass changes its position. it says that the wire has magnetism。
Then the professor cut the iron wire to two small wires, and put one of the small wire's one side near the compass , the arrow in compass changes its position as well, and then put another side and the arrow in compass changes its position to oppisite direction. it is said that the iron wire also has two poles./
in this photo, we use the equation to find the magnetic flux
in this photo, when we make the area and magnetic induction line parallel, we know that the magnetic flux is 0
in this photo,the professor gives us a oscillooscope and put a magnet near it, and we find that when magnet in different position and move, the bright point will go different direction,.
in this photo, we figure out two vectors of points and how the point move.
In this photo, professor gives us an equation to find the unit of B . and we know that the unit of F is N, q is C, v is m/s and we get that the unit of B, T=N/A*m
in this photo, we did an exericse about the force of charge in magnetic field.
in this photo, we use the equation F=qvB to find the F is 6.25*10^-16 and the acceleration a= 3.74*10^11m/s
in this photo, professor let us to prdict the motion of the charge when put it into magnetic field. and we find the motion is circle motion and we know that F=qvB=mv^2/r and we find the radius r=mv/qB
in these two photos, we use the equation r=mv/qB and v=2pirf to find the B is 0.0875T
Then in these two photos, the professor put a wire line in the magnet and make the connect the line to battery. and we find when the wire connect to the battery, the wire will change its position, up or down.
then we do the questions in this photo.
For a, t=L/v
For b, I=q/t
For c, we got that F=qvB=ILB
For d, it is in the second photo, dF=IdLB
in this photo, we begin to do experiment about the loop.
in this photo, the direction of magnetic filed is from left to right, and the direction of current is clockwise，we draw the Fand its direction and we find that the top and bottom has no force and the direction of F of left is inside the table and the right is outside the table.so the loop will rotate /
in this photo, we change the direction of magnetic filed to from outside to inside, and the current is also clockwise and we find that the force of 4 sides are same but the directions are to 4 different direction, so the loop will not move.
Then the professor let us make a prediction about how the loop will move and we think it will spin up 90,because we did the two different solutions before.
Conclusion:
Today, in class, we learned about magnetism and its properties. We
saw how the magnetic fields looks like on the magnet. Then we learned
about the right hand rule when it comes to currents and force. We also saw that
current, length and magnetic field determine the force of the magnetic field. When it is given magnetic charge by being placed
in a horseshoe magnet and cut into half, the magnetic charge is shown by using
a compass.
No comments:
Post a Comment