文档介绍：AP Physics – ism 2
If a moving charge has a force exerted on it when it goes through a ic field, shouldn’t the force be even more impressive on a stream of particles, like an electric current flowing through a conductor?
Well, by golly, yes!
Each electron has a force exerted on it by the ic field. The force is transferred to the conductor by the collisions the electrons have with the atoms in the conductor.
In the drawing below we have a ic field between the two s. A current carrying wire passes between the and a force is exerted on it, pushing it up. We can use the right hand rule to figure out the direction of the force. Point your fingers from north to south (direction of the field) and your thumb in the direction of the current. Your palm points up and this is the direction of the force. Just like we did with a single charged particle.
The magnitude of the force exerted on a straight length of wire by the ic field is given by the following equation.
Where FB is the ic force, I is the current, l is the length of the wire, and q is the angle between the wire and the ic field.
You will have the use of this equation on the AP Physics Test.
If the ic field is perpendicular to the wire (like in the drawing above), then the angle q is y degrees and the sine of the angle is one. This is when the current will have its maximum value.
Note that if the field and the current are in the same direction, no force is exerted on the conductor.
A wire has a current of A. It goes east to west. The ic field goes south to north and is horizontal. The ic field strength is 55 mT. Find the force acting on a 25cm length of wire.
The ic field is perpendicular to the direction of the current, so we have a maximum force.
We can find the direction of the force using the right hand rule:
The direction of the force is down.
ic Field and Conductors: We’ve learned that a ic field can affect an electric current – exert a force on the conductor. Do you suppose it is