Magnetic forces on current-carrying wires

Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
43 replies · 4K views
MartinCarr said:
See the attached file on the above post..
i've already seen it but i don't understand. can you please explain it to me based on the question i asked above.
 
on Phys.org
How about answering the question I posed earlier?
Doc Al said:
So what additional force must wire Z exert on X to produce the given resultant?
You are given the resultant F/L on wire X. You've calculated the contribution from wire Y. So, what must be the contribution from wire Z? That will tell you the direction of the current in Z and allow you to calculate the magnitude of that current.
 
Doc Al said:
How about answering the question I posed earlier?

You are given the resultant F/L on wire X. You've calculated the contribution from wire Y. So, what must be the contribution from wire Z? That will tell you the direction of the current in Z and allow you to calculate the magnitude of that current.
2.5x10^-4 . is it right?
 
Did you work this out or do you need me to explain more?
 
hooman said:
2.5x10^-4 . is it right?
Don't just give a numeric answer. Describe how you got your answer. And what does that tell you about the direction and magnitude of the current through Z?
 
MartinCarr said:
Did you work this out or do you need me to explain more?
explain please
 
Doc Al said:
Don't just give a numeric answer. Describe how you got your answer. And what does that tell you about the direction and magnitude of the current through Z?
from the question a, i need to know the direction whether it is right or wrong. so, fron the diagram itself we can know whether it is right or wrong. but i don't know how. i cannot determine the direction by using calculation because how can i know the equation have to use minus or addition.
 
MartinCarr said:
Did you work this out or do you need me to explain more?
the statement is wrong. the right one is the resultant force per unit length is actually acted on Y not on X. it's a mistake in typing the question. sorry. so how to determine the direction whether it's right or wrong?
 
Doc Al said:
Don't just give a numeric answer. Describe how you got your answer. And what does that tell you about the direction and magnitude of the current through Z?
the statement is wrong. the right one is the resultant force per unit length is actually acted on Y not on X. it's a mistake in typing the question. sorry. so how to determine the direction whether it's right or wrong?
 
hooman said:
the statement is wrong. the right one is the resultant force per unit length is actually acted on Y not on X. it's a mistake in typing the question.
At least that explains the "towards X" statement.
hooman said:
so how to determine the direction whether it's right or wrong?
Do you know how to find the force/length between two current-carrying wires? Start there.

Try this: Magnetic Force Between Wires
 
Doc Al said:
At least that explains the "towards X" statement.

Do you know how to find the force/length between two current-carrying wires? Start there.

Try this: Magnetic Force Between Wires
what does it means by pointing towards X? yes, I do know how to find F/l
 
Doc Al said:
At least that explains the "towards X" statement.

Do you know how to find the force/length between two current-carrying wires? Start there.

Try this: Magnetic Force Between Wires
but, in the question in the link that you gave, i don't know how to do it because the question itself doesn't give any value
 
As we know a current carrying wire will induce a magnetic field around it. This field will be clockwise around the wire in the direction of current. Both wire Y and Z will exert a force on X.

By looking at the direction of the magnetic field from Y and then Z at the side of X (either into or out of the paper) you can use the hand rules (movement, flux & current) you can work out which way the wire will move.

Using the formula in the attachment you can then calculate the force and hence the direction and value of current in the question.
 
Considering the figure as it is ,
Force on X due to Y is towards left
Force on X due to Z is towards right.
As net force on X is towards left ( see the attachment ).
F(y) > F (z).
F (net) = F(y) - F( z)
50 x 10^(-5) = 25 x 10^ (-5) - (20xI /6) x 10^(-5)
Solving we get negative value for I which is meaningless . In my opinion it should not be.
So direction of current in Z should be downward.
Then due to both Y and Z forces will be towards X.
 

Attachments

  • 20200422_232117.jpg
    20200422_232117.jpg
    28.6 KB · Views: 168