Force in a magnetic field. Need help using the equation

[crh]

Homework Statement

What is the magnitude of the force per meter of length on a straight wire carrying a 6.70-A current when perpendicular to a 0.89-T uniform magnetic field?

What if the angle between the wire and field is 45.0°?

I know how to do the whole thing, I just can't get my answer right. I don't know if I am working the equation out right.

Homework Equations

F=IlBsin$$\theta$$

The Attempt at a Solution

Using the above equation. For part A I know that I use it for 90 degrees at 1m

F=(6.70A)(0.89T)sin90=5.9N/m

Part B is the one I can't get the answer to.

F=(6.07A)(0.89T)sin45

**I haven't had a trig class or a physics class for about 7 years so I don't remember how to exactly use sin. For Part A I got the correct answer because I just didn't use the sin. I just took the (6.70A*0.89T). Can someone explain how to use sin or how to get the right answer. I got 5.07 N/m but that is not correct.

Thanks in advance to everyone that helps.

 

[gabbagabbahey]

It sounds like you had your calculator set to radians instead of degrees.

1 degree = pi/180 radians so 45 degrees= 45pi/180 =pi/4 radians

Try using that as your argument for sin.

 

[baba89]

The equation you are using is correct, but the issue may be with the use of sine. In this case, sine represents the angle between the wire and the magnetic field. When the angle is 90 degrees, sine is equal to 1, which is why you got the correct answer for part A. However, when the angle is 45 degrees, sine is equal to √2/2, which is approximately 0.707. This means that the force will be smaller than the force at 90 degrees.

To solve for the force in part B, you can use the following equation:

F = (6.70 A)(0.89 T)sin(45°) = (6.70 A)(0.89 T)(0.707) = 4.74 N/m

Remember to always convert the angle to radians when using the sine function. In this case, 45 degrees is equivalent to π/4 radians.

I hope this helps in getting the correct answer. Just make sure to always check your units and use the correct formula. Good luck with your homework!