Finding B field within solenoid.

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SUMMARY

The discussion focuses on calculating the magnetic field (B field) inside a solenoid with 10,000 turns per meter and a straight wire segment of 0.05 meters length, carrying a current of 14A. The formula for the magnetic field inside the solenoid is B = μ₀nI, where μ₀ is the permeability of free space (4π x 10^-7 T·m/A). The user struggles to incorporate the magnetic field from the straight wire, which follows the equation B = (μ₀I)/(2πr). The challenge lies in determining the correct radius (r) for the wire's magnetic field and understanding how to combine the two magnetic fields effectively.

PREREQUISITES
  • Understanding of electromagnetism principles, specifically solenoids and magnetic fields.
  • Familiarity with the Biot-Savart Law and Ampère's Law.
  • Knowledge of the right-hand rule for determining the direction of magnetic fields.
  • Basic algebra for manipulating equations involving magnetic fields.
NEXT STEPS
  • Study the derivation and application of the Biot-Savart Law for calculating magnetic fields around current-carrying conductors.
  • Learn about the superposition principle in electromagnetism to combine multiple magnetic fields.
  • Explore practical examples of solenoid applications in physics and engineering.
  • Review the concept of magnetic field lines and their interactions in different configurations.
USEFUL FOR

Physics students, electrical engineers, and anyone interested in understanding magnetic fields generated by solenoids and current-carrying wires.

Alouette
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1.
A current balance is constructed to measure the force between a solenoid with n=10000turns per length and a straight wire segment of length l=0.05m inside the solenoid and perpendicular to the field. The current through both the solenoid and wire segment is I=14A. What is the B field inside the solenoid?

2.
B = μonI (solenoid)

B = (μoI)/(2∏r) (straight wire)3.
I've gone over notes and the chapter, but seeing as I'm still struggling, would like some insight.

Drawing a diagram, on xy-plane I drew the solenoid on x-plane and since it says the wire is perpendicular to it, it is on the y-plane cutting across the solenoid.

My first attempt was to simply use the equations stated above and plug in the numbers:
μonI = (4∏ x 10^-7)*(10,000/0.05)*(14) = 3.52
Obviously wrong since it doesn't involve the straight wire segment.

Trying to use the equation for straight wire is of no use because of the r which I don't seem to have.

I go back to my drawing, RH rule suggests the wire has B field curling around it, while next to it, the solenoid's B field which loops around is there. Showing how little I know but my next thought was to add the two B fields, answer not different from first attempt. This is where I'm stuck.

Besides missing the concept, am I missing something obvious, or am I going to get the response of going to the book once again...
 
Last edited:
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Not even one tiny help? I'm not even looking for much.
 

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