Find the magnitude of the magnetic force on the power line.

+3 votes

A horizontal power line of length 53.2 m carries a current of 2.16 kA northward as shown in the figure below. The Earth's magnetic field at this location has a magnitude of 4.50 image 10-5 T. The field at this location is directed toward the north at an angle 65° below the power line.

image

(a) Find the magnitude of the magnetic force on the power line.
N

(b) Find the direction of the magnetic force on the power line.

    
asked Feb 19, 2012 in Physics by Joey33 ~Expert~ (1,216 points)
    

1 Answer

+4 votes
 
Best answer

The formula for magnetic force is:

magnetic force = I*L X B (where I=current, L=length, X=cross product, and B=magnetic field)

which can be rewritten as:

magnetic force = I*L * B * sin(theta) (*where theta is the angle between the length and the magnetic field)

 

we are given:

I =  2.16 kA = 2160 A

L =  53.2 m

B = 4.50 image 10-5 T

theta = 65 degrees

plugging into the equation we get:

 

magnetic force = I*L * B * sin(theta)

magnetic force = (2160 A) * (53.2 m) * ( 4.50 image 10-5 T)* sin(65)

magnetic force = 4.687 N

 

Part B, find the direction of the magnetic force by using the Right Hand Rule

For help on using the right hand rule refer to this question:

http://answermenu.com/?qa=367/direction-positively-particle-situations-direction-indicated

After applying you will find that the force is going "into the screen"

answered Feb 23, 2012 by kirby ~Expert~ (3,020 points)
selected Feb 23, 2012 by Joey33

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