# Physics -work shown

posted by on .

A heavy conductor (mass m, length `, resistance R) is suspended by two springs each with spring constant k, and connected to a battery with electric potential V as shown in
the figure. A magnetic field ~B is now imposed. The acceleration of gravity is 9.8 m/s2 .
Which direction should the magnetic field point to have the most effect in raising the heavy conductor?
1. Out of the page
2. Into the page
3. Vertically downward in the plane of the page
4. The direction of the magnetic field is irrelevant.
5. To the left in parallel to the the conductor
6. Vertically upward in the plane of the page
7. In the plane of the page at a 45 degree angle to the conductor
8. To the right in parallel to the conductor

The key is the direction of the current, and the direction of B in relation to the conductor.
Still not sure here is the sketch...

---------- + - -------
| V |
| |
Spring K Spring K
| |
| |
<----------l--------->
Heavy Conductor R
|
mg

I selected #1 AND IT WAS INCORRECT. I guess I just don't understand...

• Physics -work shown - ,

If I understand your diagram, current goes to the right on the bottom, I use my right hand, and see then below the wire B from current going inward to the page. To raise the conductor, B has to go into the page also.

• Physics -work shown - ,

Thank you so much! I am struggling through this class. The professor is so intellegent that he doesn't bring it down to the basics for understanding.