Motional EMF (direction of moving bar)

  • Thread starter Thread starter sandy.bridge
  • Start date Start date
  • Tags Tags
    Emf Motional emf
AI Thread Summary
To determine the direction of the velocity of a conducting bar inducing a current, the magnetic force (Fb) and gravitational force (Fg) must be analyzed. The equation Fb=q(VxB) can be simplified to F=ILxB for clarity. In a steady state where Fb exceeds Fg, the motional emf does not equate to Fb-Fg directed to the right, as the magnetic force opposes the motion. The confusion arises from the relationship between the induced current and the magnetic force, which can sometimes appear counterintuitive. Understanding that the magnetic force always opposes the direction of motion is crucial for accurately determining the system's behavior.
sandy.bridge
Messages
797
Reaction score
1

Homework Statement



Can someone please explain to me how to determine the direction of the veloicty of a bar that is conducting and inducing a current.

Fb=q(VxB)?
 
Physics news on Phys.org
Use F = IL x B instead.
 
Consider a conducting wire attached to a small weight. Fg acts to the right, and Fb (due to magnetic field perpendicular) is directed to the left. Say Fb>Fg. If the system is allowed to reach "steady state" why is the motional emf not Fb-Fg and directed to the right?
 
The only reason I am asking is that I read that the magnetic force that develops due to a velocity always has to oppose it... Which doesn't seem like it would always be the case. Especially if there is a current passing through the wire such that it is that force giving it the acceleration.
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

The Magnitude of Induced EMF in a Moving Rod?
Replies
8
Views
4K
Motional EMF in the presence of a time-varying magnetic field
Replies
11
Views
3K
Making sense of sequence of ideas in MIT OCW's 8.02 notes on Faraday
Replies
1
Views
1K
EMF due to Lorentz electric and magnetic forces
Replies
3
Views
1K
What is the induced magnetic force on this closed current loop?
Replies
12
Views
2K
Induced EMF in a Triangle: Determining EMF and External Force
Replies
3
Views
3K
Induced EMF in a moving Loop Conductor
Replies
3
Views
2K
Electromagnetism EMF induction calculations
Replies
9
Views
2K
How Accurately Can Induced EMF Represent Batteries in Circuit Problems?
Replies
8
Views
2K
EMF and potential in a circuit
Replies
2
Views
1K

Hot Threads

Recent Insights

Back
Top