Does Dropping a Wire in Different Geographic Directions Induce EMF?

[kihr]

I have a conceptual issue with the following:

Whether a length of metallic wire, if placed in the geographic (a) east-west, and (b) north-south directions, and dropped freely from a height would have an induced emf or not.
My understanding is as follows:

The magnetic field of the Earth has a vertical and a horizontal component, both of which lie on the magnetic meridian. The horizontal component (in the plane of the magnetic meridian) would further have components along the geographic N-S and E-W directions (i.e. along the length of the wire) depending on the magnetic declination at the given point on the Earth's surface. Thus for both (a) and (b) the falling piece of wire would move parallel to the horizontal and vertical components of the Earth's magnetic field in the plane in which the wire falls. For emf to be induced, the wire must cut the magnetic field. Since this does not happen in either of (a) or (b), there will be no induced emf in the wire as it falls.

I would appreciate if the correctness of my understanding could be ratified. Many thanks.

 

[eljose79]

I can confirm that your understanding is correct. In order for an emf to be induced in a wire, it must cut through the magnetic field lines. In the case of the wire falling in either the east-west or north-south directions, the wire would be moving parallel to the magnetic field lines and therefore would not cut through them. This means that there would be no change in magnetic flux, and therefore no induced emf in the wire.

Additionally, the strength and direction of the Earth's magnetic field can vary depending on location, making it difficult to predict whether or not there would be an induced emf in the wire even if it were to fall at an angle to the horizontal or vertical components of the field.

I hope this helps clarify any confusion and please let me know if you have any further questions. Thank you for your interest in science!

 

[astrokreng]

Your understanding is correct. In order for electromagnetic induction to occur, there must be a change in the magnetic field that the wire is cutting through. In the case of a falling wire in the east-west or north-south directions, there is no change in the magnetic field, as the wire is moving parallel to the field. Therefore, there will be no induced emf in the wire. This is also known as Faraday's Law of Induction, which states that a changing magnetic field can induce an electric current in a conductor. In this scenario, there is no change in the magnetic field, so no current will be induced.