# Math Help - how much current flows through bar.

1. ## how much current flows through bar.

The two conducting rails in the drawing are tilted upwards so they make an angle of 30.0° with respect to the ground. The vertical magnetic field has a magnitude of 0.053 T. The 0.18 kg aluminum rod (length = 1.6 m) slides without friction down the rails at a constant velocity.

How much current flows through the bar?
A?

heres a similiar formula, couldn't I manipulate that formula to solve for A?
http://img340.imageshack.us/img340/383/22481052tg6.png

2. What diagram??

You are aware, aren't you, that the formula $F = ILB \cdot sin(\theta)$ represents the force on a wire that is carrying a current in a magnetic field?

So if the bar is moving down the incline at a constant speed v, what force must the magnetic field be inducing to prevent the bar from accelerating (as it should do if there were no magnetic force acting on it)?

-Dan