JEE · Physics · Magnetism & Matter doubts
8 doubts found
Why is soft iron used in a transformer core but steel is used for a permanent magnet?
A transformer reverses magnetisation every AC cycle, so its core should magnetise and demagnetise easily with little energy loss.
A compass is carried from the magnetic equator toward a magnetic pole. What changes?
At the magnetic equator, dip is approximately zero and Earth's field is nearly horizontal.
What does “Magnetic dipole moment” actually mean in Magnetism & Matter, and why does it matter for JEE?
A bar magnet behaves like a magnetic dipole. Its moment points from south to north inside the magnet and determines the torque m x B in an external field.
I keep getting “Magnetic dipole moment” questions wrong in Magnetism & Matter. What's the trap?
reversing the magnetic moment direction because external field lines run north to south.
What does “No isolated magnetic poles” actually mean in Magnetism & Matter, and why does it matter for JEE?
Cutting a bar magnet produces smaller north-south dipoles, not separate monopoles. Therefore net magnetic flux through any closed surface is zero.
I keep getting “No isolated magnetic poles” questions wrong in Magnetism & Matter. What's the trap?
expecting a cut magnet to leave one north-only and one south-only piece.
What does “Earth as a magnetic field” actually mean in Magnetism & Matter, and why does it matter for JEE?
Locally, Earth's field is described by declination, dip (inclination), and horizontal component. Dip is measured from the horizontal plane, not from the vertical.
I keep getting “Earth as a magnetic field” questions wrong in Magnetism & Matter. What's the trap?
interchanging declination and dip.