Current in wire loop inside a solenoid

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Homework Help Overview

The problem involves a solenoid with specific dimensions and characteristics, including its length, diameter, number of turns, and the rate at which the current is increasing. The original poster is attempting to understand how to apply Faraday's law in the context of the magnetic field generated by the solenoid and its effect on a wire loop that is larger than the solenoid.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster considers finding the magnetic field inside the solenoid and applying Faraday's law. They express uncertainty about how to treat the current since it is given per unit time. Some participants suggest relating the current in the solenoid to the magnetic field produced and question the implications for a larger loop surrounding the solenoid.

Discussion Status

Participants are actively engaging with the problem, exploring the relationship between the solenoid's current and the magnetic field, as well as the implications for a larger loop. Some guidance has been offered regarding the treatment of the magnetic field and the area of the loop, indicating a productive direction in the discussion.

Contextual Notes

There are questions regarding the behavior of the magnetic field outside the solenoid and how it affects the current in a larger loop. The dimensions of both the solenoid and the larger loop are specified, which may influence the discussion on magnetic flux.

gills
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Homework Statement


A 2.1m -long solenoid is 13.0cm in diameter and consists of 2200 turns of wire. The current in the solenoid is increasing at the rate of 1.0 kA/s .


The Attempt at a Solution



Any help to point me in the right direction would be great.

I'm thinking that i need to find the magnetic field inside that of a larger solenoid. Then i somehow manage to put that into faradays law equation.
 
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That is exactly what you have to do. Good thinking.

HINT: How can you relate the current in the solenoid to the B-Field produced?
 
G01 said:
That is exactly what you have to do. Good thinking.

HINT: How can you relate the current in the solenoid to the B-Field produced?

how do i treat the current since it is given per unit time? That is throwing me off.

B(solenoid) = [tex]\mu[/tex][tex]_{0}[/tex]*n*I ---> ??
 
ok this is what I've got

dB/dt = [tex]\mu[/tex][tex]_{0}[/tex]*n*[tex]\frac{dI}{dt}[/tex]
 
gills said:
ok this is what I've got

dB/dt = [tex]\mu[/tex][tex]_{0}[/tex]*n*[tex]\frac{dI}{dt}[/tex]

ok, got the first part.

What about when there's a loop that is larger than the solenoid? Would the current in that loop be zero since the magnetic field outside of solenoid is almost neglible?

The diameter of the larger loop is 19.5cm
 
gills said:
ok, got the first part.

What about when there's a loop that is larger than the solenoid? Would the current in that loop be zero since the magnetic field outside of solenoid is almost neglible?

The diameter of the larger loop is 19.5cm

ok, nevermind on that one. Would i just be changing the area of the loop from the equation i derived in the first problem or is there more to it?
 
gills said:
ok, nevermind on that one. Would i just be changing the area of the loop from the equation i derived in the first problem or is there more to it?

Yes, the only difference when the loop is bigger than the solenoid is the area of the loop. (The magnetic flux still goes through the loop if it's bigger than the solenoid.)

Keep working at it, you seem to be making some nice progress on this problem. Keep it up!:approve: If you have any more questions I'll answer them as soon as I can.
 

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