Magnetic Field Question. Grade 12 Physics.

[ampa23]

Look at picture attached
I need help with part A

Homework Statement

B=0
I = 10 A
Distance from Wire A to C is 0.05 m
Distance from Wire I to C is 0.15 m
I of wire i= ?

Homework Equations

B= U ( I / 2pi r )

The Attempt at a Solution

Ok so from Wire A to C

B1 = U (I / 2pi r)
B1= [2x10^-7(10)]/0.05
B1= 4x10^-5 T

From Wire B to point C
r=0.15 m
B2= U (I/2pi r)
B2= [(2x10^-7)(I)]/(0.15)


OK so in the question there going in different directions and at that point it equals 0
So do i subtract them even if the point is outside the 2 wires?

0 = B1 - B2
B2 = B1
and then solve

or would i have to add them together?

0 = B1 + B2
B2=-B1
and then solve?

Im confused since point C is outside of the 2 wires.

I know for Part B you would subtract.

Thank You

 

[cupid.callin]

Hi ampa23
Welcome to PF!

From thumb rule you can see that for left wire B is out of plane and for right wire B is into plane

and for your eqn, just use that their magnitudes shall be equal
ie B1 = B2

 

[ampa23]

Thank you, but then for part B of this question would you subtract the 2 B values to find the Net B or would you subtract them?

 

[cupid.callin]

Thank you, but then for part B of this question would you subtract the 2 B values to find the Net B or would you subtract them?

Use the thumb rule and tell me

 

[ampa23]

loll I am guessing you subtract them :P

 

[cupid.callin]

Think again ...

You know how to use thumb rule, right?