What would the voltmeters measure?

  • Thread starter Thread starter JACKR
  • Start date Start date
  • Tags Tags
    Induced Rod
Click For Summary
SUMMARY

The discussion centers on the measurement of voltage (emf) in a conducting rod moving through a magnetic field. The participants clarify that while the induced emf in the rod is expressed as BLv, this is not sufficient to determine the voltage readings accurately. Specifically, they highlight that the resistance of the rod and the U-shaped loop is zero, which significantly impacts the voltage measurements, leading to V1 reading zero and V2 reading 2B(L'-L)v.

PREREQUISITES
  • Understanding of electromagnetic induction principles
  • Familiarity with the Lorentz force law
  • Knowledge of voltage measurements in electrical circuits
  • Concept of resistance in conductive materials
NEXT STEPS
  • Study the principles of electromagnetic induction in detail
  • Learn about the Lorentz force and its applications in electrical engineering
  • Explore voltage measurement techniques in circuits with zero resistance
  • Investigate the effects of resistance on induced emf in conductive materials
USEFUL FOR

Electrical engineers, physics students, and anyone interested in the principles of electromagnetic induction and voltage measurement 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   Reactions: SammyS and Steve4Physics

Similar threads

Replies
4
Views
909
Replies
5
Views
1K
  • · Replies 27 ·
Replies
27
Views
3K
Replies
8
Views
3K
Replies
11
Views
3K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 17 ·
Replies
17
Views
1K
  • · Replies 8 ·
Replies
8
Views
4K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K