Posted by **Rachel** on Saturday, April 9, 2011 at 11:46am.

Two very long, straight, parallel wires carry currents that are directed perpendicular. Wire 1 carries a current I1 into the page (in the -z direction) and passes through the x axis at x = +a. Wire 2 passes through the x axis at x = -2a and carries an unknown current I2. The total magnetic field at the origin due to the current-carrying wires has the magnitude 2µ0I1 / ( 2πa ). The current I2 can have either of two possible values.

Find the value of I2 with the smaller magnitude, stating it in terms of I1 and giving its direction.

I have to write formula

thank you

- physics -
**bobpursley**, Saturday, April 9, 2011 at 12:37pm
Not exactly write a formula. You have to analyze the problem, then derive the formula. We don't write formulas in Physics, the Creator did that.

Here first find the distance between wires (so what is the distance between x=-2a and x=a) The force at the origin? Well it is the sum of the two forces from each wire.

Force from wire1 is kI/(2pi*distance)

http://dev.physicslab.org/Document.aspx?doctype=3&filename=Magnetism_CurrentCarryingWires.xml

The other force is similar, but the distances are different.

Now signs. Use your right hand rule, and determine the force direction for each wire. You dont know the direction for current I2, but if it is into the page, then the force subtracts from the first force.

Well, add the forces, with the +- force for the second force.

## Answer this Question

## Related Questions

- Physics - (the drawing is of a square with each side equaling L and the ...
- Physics - Two long straight wires are perpendicular to the page and located at ...
- Physics - Two long, straight, parallel wires carry current in the same direction...
- Physics - Two long, straight, parallel wires carry current in the same direction...
- College Physics - A very long wire carries an I1 = 7.80 A current along the x ...
- Physics - Two long parallel wires separated by a distance, d, carry currents in ...
- physics - Two straight and parallel wires of length 1.0 m carry a current — the ...
- PHYSISC - Two parallel, straight wires that are very long are separated by a ...
- Physic please check - A +6.00 µC charge is moving with a speed of 7.00 x 10^4 m/...
- Physics - The figure below shows two current carrying wires and the directions ...

More Related Questions