Question

magnetic needle making different angles with the horizontal when suspended at different places of earth at different places on earth

Answer 1

Answer:

I'm studying electromagnetic radiation from Jackson's book, but I have a question. I understand that electromagnetic radiation is the flux of electromagnetic energy to infinity, according with Griffiths' definition, but I have a problem; When Jackson (Third Edition 1999, page 408) consider a localized oscillating source and calculate the vector potential A, he takes the limit d≪λ, where d is the characteristic dimension of the source and λ is the characteristic wavelength of the fields.

Answer 2

Answer:

• If a magnetic needle is suspended in a vertical plane and taken around the earth through the geographic poles, we find that at two points, the magnetic needle becomes normal to the earth's surface (i.e., the needle becomes vertical) and at two points, it becomes parallel to the earth's surface (i.e., the needle becomes parallel to the earth's surface) (i.e., it becomes horizontal).
• In other places, as shown in the figure, it rests at various angles with the horizontal. It implies that the earth's magnetic field exists.
• When a magnetic needle is suspended freely, it always aligns itself in the direction of the earth's magnetic north-pole and south-pole, with the north pole of the needle being attracted to the magnetic south pole and the south pole being repelled equally away from it.

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