How to find speed with Faraday's law

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SUMMARY

This discussion focuses on applying Faraday's law to a physics problem involving a metal rod sliding on a rail within a uniform magnetic field of B=1T. The key equations used include F=IBl and the relationship between magnetic flux and area change. The force required to maintain a constant speed of v=10m/s is calculated to be 1N, while the work dissipated on the resistor after the rod is released is determined to be 2J. Participants emphasize the importance of understanding the derivation of formulas to effectively solve such problems.

PREREQUISITES
  • Understanding of Faraday's law of electromagnetic induction
  • Familiarity with the concept of magnetic flux (Φ)
  • Basic knowledge of electric circuits and resistance (R)
  • Ability to apply Newton's laws of motion in physics problems
NEXT STEPS
  • Study the derivation of Faraday's law and its applications in electromagnetic systems
  • Learn about the relationship between magnetic flux and area change in moving conductors
  • Explore the concept of induced electromotive force (EMF) in circuits
  • Investigate the principles of energy dissipation in resistive components
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Students studying electromagnetism, physics educators, and anyone interested in understanding the practical applications of Faraday's law in electrical engineering and physics problems.

Jacobs
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Homework Statement


A metal rod can slide on a rail without any friction in the presence of uniform magnetic field of B=1T which is perpendicular to the plane of the paper.The distance between the tracks is d=0.1m and the resistance given is R=0.1 ohm.The resistance of the rail is negligible and the mass of the rod is m=20g. A)How much force must be on the road exerted in order to move it with a constant speed of v=10m/s? B)The rod has been moved for t=2s and then it is released.How much work is dissioated on the resistor till the rop will stop?

Homework Equations


F=IBl=B^2*l^2*v/R

The Attempt at a Solution


According to first formula F=1 but for B i have no idea
 
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Welcome to the PF.

Could you please post the figure that goes with this question? It sounds like a classic sliding rail changing the total B*dA, but it's hard for me to be sure from the text of your post. Thanks. :smile:
 
1st one
 

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You might start here. http://hyperphysics.phy-astr.gsu.edu/hbase/electric/farlaw.html

The rails and the rod and resistor make an electric loop. You can find the area of that loop if you know the length, but for this problem, you are interested in the Change in the area when the rod moves. Since Phi = B*A, phi can change if B changes or (in your case) when A changes. It doesn't do a whole lot of good to have some formulas, unless you have an idea of where they come from. Then you'll understand which ones to use.
 
so formula is BdeltaA/delta(t) but still have no idea about how find find change in the area
 
Answer of B is 2?
 
Jacobs said:
so formula is BdeltaA/delta(t) but still have no idea about how find find change in the area
The motion of the movable rod changes the area.
Jacobs said:
Answer of B is 2?
Please always show your detailed work so we can check it. Thank you.
 
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