Emf of coil outside a solenoid

[supersunshine]

Homework Statement

A coil of 120 turns and radius of1.8 cm and resistance of 5.3 ohm is placed outside a solenoid. If the current in the solenoid is changed, what current appears in the coil while the solenoid is being changed?

Homework Equations

emf= -dflux/dt = A*dB/dt

emf=iR

Bsol= nui

The Attempt at a Solution

To solve this problem, first you would need to find the emf induced in the coil by the changing current in the solenoid, and then the current by i=emf/R
but I am confused how to apply this. my questions is;

1) to use emf= -dflux/dt, does this apply to the area of the solenoid or coil? i thought solenoid, but we are only given information about the coil

thank you for your help

 

[anathema]

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To answer your question, the equation emf= -dflux/dt applies to the coil in this situation. This is because the coil is the object in which the emf is being induced by the changing magnetic field of the solenoid. The solenoid itself is not changing, so the flux through it remains constant. Therefore, the emf induced in the coil is due to the changing magnetic field produced by the solenoid.

To calculate the emf induced in the coil, we can use the equation emf= -N*dflux/dt, where N is the number of turns in the coil and dflux/dt is the rate of change of magnetic flux through the coil. In this case, the magnetic flux through the coil is changing due to the changing current in the solenoid. We can use the equation Bsol= nui to calculate the magnetic field produced by the solenoid, where n is the number of turns per unit length, u is the permeability of the medium, and i is the current in the solenoid. We can then use this value for Bsol in the equation for dflux/dt to calculate the emf induced in the coil.

Once we have the emf induced in the coil, we can use the equation emf=iR to calculate the current in the coil. This will give us the current that appears in the coil while the solenoid is being changed.

I hope this helps clarify the process for solving this problem. Let me know if you have any further questions. Good luck with your calculations!

 

[m2003]

I would approach this problem by first understanding the basic principles of electromagnetic induction. The emf equation, emf = -dflux/dt, applies to the area through which the magnetic flux is changing. In this case, the magnetic flux is changing through the area of the coil, as the solenoid is being changed. Therefore, we can use the emf equation to calculate the emf induced in the coil.

Next, we can use Ohm's law, emf = iR, to calculate the current in the coil. Since we are given the resistance of the coil, we can use the emf calculated from the previous step to solve for the current.

It is important to note that the current in the coil will depend on the rate of change of current in the solenoid, as well as the physical properties of the solenoid and coil. Therefore, the current in the coil will change as the current in the solenoid changes.

In summary, to solve this problem, we would need to use the emf equation and Ohm's law, and take into consideration the physical properties of the solenoid and coil.