Calculate Force and Direction of Magnetic Field on a Wire

[davidelete]

Homework Statement

A wire 3.0 cm long lies perpendicular to a magnetic field with a magnetic induction of 0.40 T. Calculate the force on the wire if the current is 5.0 A. What is the direction of force?

Homework Equations

F=BIL

The Attempt at a Solution

I found the force to be .06 N but I have no idea how to find the direction.

Homework Statement

A wire 1.5 m long is at right angles to a magnetic field.

a. What is the magnetic induction of the field if the force on the wire is 1.5 N and the current is 0.050 A?

b. What is the force on the wire if it is rotated 90 degrees?

Homework Equations

F=BIL

The Attempt at a Solution

a. The answer is 20 Teslas.

b. I have no idea? Would it be zero because they are not perpendicular any more?

 

[rl.bhat]

I have no idea how to find the direction.
Perpendicular to the plane containing wire and magnetic field.
I have no idea? Would it be zero because they are not perpendicular any more?
It depends upon how the wire is rotated.

 

[nlightner]

I would like to provide some clarification and guidance on this problem.

First, it is important to understand that the direction of the force on a wire in a magnetic field is determined by the right-hand rule. This rule states that if you point your thumb in the direction of the current, and your fingers in the direction of the magnetic field, then your palm will face in the direction of the force.

Now, for the first problem, we can use the equation F=BIL to calculate the force on the wire. Plugging in the given values, we get F=(0.40 T)(5.0 A)(0.03 m) = 0.06 N. This means that the wire will experience a force of 0.06 N in the direction perpendicular to both the current and the magnetic field. To determine the direction of the force, we can use the right-hand rule. If the current is flowing from left to right, and the magnetic field is directed into the page, then the force will be directed downwards.

For the second problem, we are given the force and current, and we need to find the magnetic induction of the field. Rearranging the equation F=BIL, we get B = F/(IL). Plugging in the values, we get B = (1.5 N)/(0.050 A)(1.5 m) = 20 T. So, the magnetic induction of the field is 20 T.

For part b, you are correct in thinking that the force will be zero if the wire is rotated 90 degrees. This is because the wire will now be parallel to the magnetic field, so there will be no component of the force perpendicular to the wire.

I hope this explanation helps! Remember to always use the right-hand rule to determine the direction of the force in these types of problems.