EMF v time graph vs change in flux v time

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SUMMARY

The discussion focuses on understanding the relationship between induced electromotive force (emf) and the change in magnetic flux over time, specifically in the context of a 2007 HSC problem. The key equation discussed is emf = -ΔΦ/Δt, indicating that the magnitude of the induced emf is maximized when the flux-time graph is steepest. Participants clarify that the vertical lines in the graph do not represent maximum or minimum values but rather indicate polarity changes due to gradient variations. This insight is crucial for accurately interpreting the graphs provided in the problem.

PREREQUISITES
  • Understanding of Faraday's Law of Electromagnetic Induction
  • Familiarity with the concept of magnetic flux
  • Knowledge of calculus, specifically derivatives
  • Ability to interpret graphical data in physics
NEXT STEPS
  • Study Faraday's Law in detail, focusing on its mathematical formulation
  • Learn about the graphical representation of magnetic flux and induced emf
  • Explore the concept of gradient in calculus and its physical implications
  • Review examples of induced emf in various electromagnetic scenarios
USEFUL FOR

This discussion is beneficial for physics teachers, students preparing for HSC exams, and anyone interested in the principles of electromagnetism and their applications in real-world scenarios.

alv
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I'm actually a teacher and I can't explain this problem from the 2007 HSC. I've attached a copy of the question and the two graphs. The question shows a graph of change in magnetic flux vs time and asks you to choose which graph of induced emf best fits it. I don't understand why the induced emf is at max even while the change in flux increases (or decreases).

I've searched for help on this but can't find it. I'd appreciate any explanation you could give me.

Thanks

Homework Statement


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Homework Equations


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The Attempt at a Solution


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emf= -ΔΦ/Δt, more accurately, the negative of the time derivative of the flux. The magnitude of the emf is maximum when the flux-time graph is steepest. ΔΦ is the change of the flux in time interval Δt.
As the graph consists of linear segments, the emf is constant within one segment. The vertical lines do not mean anything.
ehild
 
Actually there's no maximum or minimum value. Just polarity change due to changes in gradient.Normally verticall line is dotted.
 
Thanks heaps for this.
 

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