Doubt in electromagnetic induction

In summary: The current would flow in the open circuit if there was no potential difference, but because there is a potential difference, the current will flow.
  • #1
Vatsal Goyal
51
6

Homework Statement


suppose a coil is placed in a changing magnetic field and the circuit is not closed will the current induce in the coil

Homework Equations

The Attempt at a Solution


What I thought was that the current flows only in a closed circuit because it needs a potential difference (through a cell) which would require a closed path, but as there is no need of a cell to create potential difference in this case, the current should flow in the open circuit. But I checked the solution and it says that a potential difference will be induced but still no current would flow.
 
Physics news on Phys.org
  • #2
You did get an EMF from the changing magnetic field. If you don't have a closed loop, current will only flow very instantaneously, and in general, only a very minute amount. An electrostatic charge will build up from this minute current flow that creates a potential that balances the EMF. It only takes a very small amount of charge to get a considerable potential for wires and most other objects. Only in the case of a very large capacitor would the flow of current be very significant, e.g. (capacitor plates at opposite sides of the wire and connected to the wire), and even then it would be minimal except with an extremely large capacitor. In general, you need a closed loop to get significant currents.
 
  • Like
Likes Vatsal Goyal
  • #3
Thank you for your answer and sorry for replying late.

I didn't understand this statement of yours completely, can you please elaborate?
Charles Link said:
It only takes a very small amount of charge to get a considerable potential for wires and most other objects

Also would this current be significant enough to be detected by a galvanometer?
Charles Link said:
If you don't have a closed loop, current will only flow very instantaneously, and in general, only a very minute amount.
 
  • #4
Approximate calculations can be done using voltages, and if you take a small conductive sphere, ## V=\frac{Q}{4 \pi \epsilon_o r} ## . If ## r=1.0 ## E-3 m (1 mm), you can see for a very small ## Q ## you can get a large ## V ##. ## \\ ## The actual equilibrium in the conductor occurs when the electric field is zero everywhere, i.e. when the electrostatic electric field is equal and opposite the induced electric field, whose integral is the EMF. Basically you can balance the EMF with the potential of the electrostatic part of the electric field, (the voltage (potential) is the integral of the electrostatic field), for approximate results. It is because so little charge is necessary to establish these voltages that our households don't use any significant electricity when nothing is plugged into the outlets. ## \\ ## There may be galvanometers that can measure small amounts of charges like you are referring to, but a standard volt-ohm meter could not measure them.
 
  • Like
Likes Vatsal Goyal
  • #5
Charles Link said:
Approximate calculations can be done using voltages, and if you take a small conductive sphere, ## V=\frac{Q}{4 \pi \epsilon_o r} ## . If ## r=1.0 ## E-3 m (1 mm), you can see for a very small ## Q ## you can get a large ## V ##. ## \\ ## The actual equilibrium in the conductor occurs when the electric field is zero everywhere, i.e. when the electrostatic electric field is equal and opposite the induced electric field, whose integral is the EMF. Basically you can balance the EMF with the potential of the electrostatic part of the electric field, (the voltage (potential) is the integral of the electrostatic field), for approximate results. It is because so little charge is necessary to establish these voltages that our households don't use any significant electricity when nothing is plugged into the outlets. ## \\ ## There may be galvanometers that can measure small amounts of charges like you are referring to, but a standard volt-ohm meter could not measure them.

Thank you, I think I got it!
 
  • Like
Likes Charles Link

1. What is electromagnetic induction?

Electromagnetic induction is the process of generating an electric current by moving a conductor through a magnetic field or by changing the magnetic field through a stationary conductor. This is based on Faraday's law of induction, which states that a changing magnetic field will induce an electric current in a conductor.

2. How does electromagnetic induction work?

Electromagnetic induction works by creating a magnetic field around a conductor, which can be a wire or a coil. When this conductor is moved through a magnetic field, or when the magnetic field around it changes, it produces an electric current. This is due to the interaction between the magnetic field and the charged particles in the conductor.

3. What are the applications of electromagnetic induction?

Electromagnetic induction has various applications in our daily lives. It is used in generators to produce electricity, in transformers to change the voltage of electric power, and in electric motors to convert electrical energy into mechanical energy. It is also used in wireless charging, induction cooktops, and many other devices.

4. What factors affect electromagnetic induction?

The strength of the magnetic field, the speed and direction of the conductor's movement, and the angle between the magnetic field and the conductor are some of the factors that can affect electromagnetic induction. The number of turns in a coil, the material and shape of the conductor, and the frequency of the magnetic field can also impact the induced current.

5. How is electromagnetic induction related to Faraday's law?

Faraday's law of induction states that the induced electromotive force (EMF) in a closed circuit is proportional to the rate of change of the magnetic flux through the circuit. This means that the induced current is directly proportional to the rate of change of the magnetic field or the speed at which the conductor is moving through the magnetic field. Electromagnetic induction is the physical phenomenon that explains this law.

Similar threads

  • Introductory Physics Homework Help
Replies
4
Views
209
  • Introductory Physics Homework Help
Replies
8
Views
2K
  • Introductory Physics Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
Replies
9
Views
349
  • Introductory Physics Homework Help
Replies
2
Views
2K
  • Introductory Physics Homework Help
Replies
2
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
3K
  • Electromagnetism
Replies
16
Views
996
  • Introductory Physics Homework Help
Replies
6
Views
857
  • Introductory Physics Homework Help
Replies
4
Views
306
Back
Top