About the experiment to find the reactance of inductor

AI Thread Summary
The experiment focused on determining the reactance of an air-core inductor versus a soft-iron core inductor, revealing distinct graph behaviors. The air-core inductor's Vrms versus Irms graph passes through the origin, while the soft-iron core inductor's graph exhibits a negative y-intercept. This discrepancy raises questions about potential errors, the linearity of permeability, and the maximum current measured. Participants suggest analyzing the χ2 values for the fits and recommend sharing plots for more detailed feedback. The discussion emphasizes the importance of understanding these results for upcoming public exams.
lindacheung66
Messages
4
Reaction score
0
I have just done an experiment on finding the reactance of (a)an air-core inductor and (b)an inductor with a soft-iron core.
I have plotted a graph of Vrms against Irms for each experiment.
For the graph in (a), the straight line can pass through origin; yet, for the graph in (b), the straight line cannot pass through the origin, but have a negative y-intercept.
However, I cannot find an answer to explain this.
Could anyone please kindly tell me why the graph in (b) cannot pass through the origin??
 
Physics news on Phys.org
It seems to be quite strange result. Have you analysed errors? What is a χ2 of the fit you made and what would be χ2 for a proportional fit (going through 0,0)?
Or maybe you went out of the linear region of permeability? What was the max current you measured and how many turns your coil has?Post your plots if you want more detailed comments.
 
Since this experiment will be counted in the public exam, I cannot post it on the internet.
Would you mind if you give me your email address so that I can send you my graphs?
 
lindacheung66 said:
Would you mind if you give me your email address so that I can send you my graphs?
Sent to you as a private message.
 
Thread 'Motional EMF in Faraday disc, co-rotating magnet axial mean flux'
So here is the motional EMF formula. Now I understand the standard Faraday paradox that an axis symmetric field source (like a speaker motor ring magnet) has a magnetic field that is frame invariant under rotation around axis of symmetry. The field is static whether you rotate the magnet or not. So far so good. What puzzles me is this , there is a term average magnetic flux or "azimuthal mean" , this term describes the average magnetic field through the area swept by the rotating Faraday...
It may be shown from the equations of electromagnetism, by James Clerk Maxwell in the 1860’s, that the speed of light in the vacuum of free space is related to electric permittivity (ϵ) and magnetic permeability (μ) by the equation: c=1/√( μ ϵ ) . This value is a constant for the vacuum of free space and is independent of the motion of the observer. It was this fact, in part, that led Albert Einstein to Special Relativity.
Back
Top