- #1
Astraithious
- 20
- 0
Homework Statement
There is a counterclockwise current I in a circular loop of wire situated in an external magnetic field directed out of the page as shown. The effect of the forces that act on this current is to make the loop
Select one:
a. expand in size X
b. contract in size
c. rotate about an axis perpendicular to the page
d. rotate about an axis in the plane of the page
e. accelerate into the page
Homework Equations
Right hand rule is all that is needed
The Attempt at a Solution
So I got this wrong for reasons I am unsure of, however this is my reasoning for choosing aThe right hand rule has many variations but this is the one i learned
My thumb is in the direction of Current or Velocity
My fingers point in the B Field direction
My palm then is the direction of the forceI can use this at any point on the circle and it pushes outwards, so should try and expand the loop right?The reasoning behind my answer being incorrect.
"The external field has lines running out of the page, which we can think of as a North pole being just under the page. The current in the wire, obeying the RHR, effectively makes a magnetic field that also has lines running up out of the page. This means that the above page part is like a north pole and the below part is like a south pole. Since this south will be attracted down by the external field north, there is an accelerating force downwards into the page."
I somewhat understand what this answer however I do not find any force directed down, is this not why things levitate when above high powered fields?