What would the voltmeters measure?

  • Thread starter Thread starter JACKR
  • Start date Start date
  • Tags Tags
    Induced Rod
AI Thread Summary
The discussion centers on the induced electromotive force (emf) in a conducting rod moving through a magnetic field. One participant asserts that the emf, calculated as BLv, is the same for two scenarios, but others challenge this assertion. They emphasize the importance of considering the Lorentz force and the zero resistance of both the rod and the U-shaped loop. Ultimately, it is concluded that the voltmeter readings differ, with V1 potentially reading zero and V2 reading an increased value of 2B(L'-L)v. The conversation highlights the complexities involved in analyzing induced emf in conductive systems.
JACKR
Messages
13
Reaction score
1
Homework Statement
I made up this problem and it is not a homework.

The tale goes like this: A rod moving with a constant speed towards the left on a U-shaped conductor in a uniform magnetic field B that is directed into the page. The width of the U-shaped conductor is L and the length of the rod is L'. V1 is connected across the part of the rod making contact with U-shaped conductor thus completing the circuit, whereas V2 is connected across the whole rod. The voltmeters are assumed co-planar with the rod as far as we're concerned and are held in a plane perpendicular to it.
Relevant Equations
ε=∮(v̅×B̅)•dl̅=-dΦ/dt
I am saying that V1=V2 since the emf induced in the rod is the same for both cases equal BLv. Am I correct?

IMG_20241107_135236.jpg
 
Last edited by a moderator:
Physics news on Phys.org
No
 
BvU said:
No
Why not?
 
JACKR said:
the emf induced in the rod is the same for both cases equal BLv
is not correct
 
BvU said:
is not correct
Yep, Why isn't it correct?
 
BvU said:
Are you familiar with the Lorentz force ?

##\ ##
Ofcourse
 
You forgot to mention the rod is conducting...
And that its resistance is zero ...
And the U-shaped loop also has resistance zero ...
(composing meaningful exercises isn't as simple as it seems :smile:)

So what does ##V_1## read ? Zero or BLv ?
##V_2## reads 2 B(L'-L)v more

##\ ##
 
  • Like
Likes SammyS and Steve4Physics
Back
Top