- #1

jcfor3ver

- 30

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## Homework Statement

First of all, the image for this problem is in an attachment (Jpeg), if you cannot view it let me know and I can change the format.

A positively charged particle moves through a region with uniform electric field pointing toward the top of the page and a uniform magnetic field pointing into the page. The particle can have one of the four velocities shown (initial speed is the same for all). Rank the four possibilities in order of increasing magnitude of the work (W1,W2,and W3) that the system would have to do on the particle to increase its speed by delta v (velocity final- velocity initial). Indicate ties where appropriate.

## Homework Equations

F=qv+Bsintheta

Work=Force*distance

Right hand rule to determine direction of Force (if you do not know this, here's a link: http://physicsed.buffalostate.edu/SeatExpts/resource/rhr/rhr.htm )

## The Attempt at a Solution

Here is my solution:

__For v1:__Force due to B and E field is in the positive y direction. Therefore to increase its speed by delta v would require the least amount of work. (since positive particle wants to move in direction of E field, a force due to the B-field in the same direction as the E field would require the least work?)

__For v2:__The force due to the B-field is perpendicular to the E-field, therefore the work required to cause the particle to speed up is equal to v4 (both are perpendicular to E)

__For v3:__The force due to B is opposite of the E-field, therefore my intuitive thought is that both forces are pushing against each other, resulting in the most Work that would have to be done by the system in order to increase the particles speed by delta v.

__For v4:__Same reasoning as v2.

Now those are my thoughts, I just am still confused on if my thinking is correct? My order would therefore be W3>W2=W4>W1