Physics 1 Marks Question

Earth's magnetic field gets weakly 'recorded' in certain rocks during solidification. Analysis of this rock magnetism offers clues to geomagnetic history.

The earth's field is only approximately a dipole field. Local north-south poles may arise due to, for instance, magnetised mineral deposits found on the surface of the earth.

The permeability of a ferromagnetic material is not less than one. It is always greater than one. Hence, magnetic field lines are always nearly normal to the surface of such materials at every point.

The magnetic moment associated with the intrinsic spin angular momentum and the orbital angular momentum.

A compass is free to move in a horizontal plane, while, the earth's field is exactly vertical at the magnetic poles. So the compass can point in any direction there.

Earth's core contains molten iron (which is the phase of the iron at the high temperatures of the core) which, is not ferromagnetic due to temperature beyond Curie temp.
Note: Ferromagnetic subtances are those which gets strongly magnetised when placed in external magnetic field.

Bisrnuth is a diamagnetic substance. Hence, a toroid with a bismuth core has a magnetic field slightly greater than a toroid whose core is empty.

Earth's magnetic field does changes with time and, the time scale for appreciable change is roughly a few hundred years. Though the change is in much smaller scale of few years, the variations are not completely negligible.

The maximum possible maqnetisanon of a paramagnetic sample can be of the sarne order of magnitude as the magnetisation of a ferromagnet. This requires high magnetising fields for saturation.

The induced dipole moment in a diamagnetic substance is always opposite to the magnetising field. Hence, the internal motion of the atoms (which is related to the temperature) does not affect the diamagnetism of a material.

Since Britain is closer to the magnetic north pole, we can expect a greater angle of dip in Britain. It's magnitude is about 70° in Britain.

Radioactivity may be one of the possible sources for the charged current in the outer conducting regions of the earth's core which is thought to be responsible for earth's magnetism.

At large distance, the field gets modified due to the field of ions in motion (in the earth's ionosphere). The field of these ions, in turn, is sensitive to extraterrestrial disturbances such as the solar wind. Hence, there is distortion in the earth's field.

The permeability of ferromagnetic materials is not independent of the applied magnetic field. It is greater for a lower field and vice versa.

Owing to therandorn thermal motion of rnolecules, the allqnments of dipoles get disrupted at high temperatures. on cooling, this disruption is reduced. Hence, a pararnaqnetlc sample displays greater magnetisation when cooled.

Melborne in Australia is situated at the southern hemisphere of the globe where, north pole of the earth's magnetic field lies.
Hence, magnetic field lines, due to the earth's magnetism would seem to come out of the ground.

A diamagnetic specimen would move towards the weaker region of the field while a paramagnetic specimen would move towards the stronger region./A diamagnetic specimen is repelled by a magnet while a paramagnetic specimen moves towards the magnet./The paramagnetic get aligned along B and the diagrammatic perpendicular.

Magnetic pole or Pole.

Steel has Higher retentivity/Higher coercivity/Higher permeability/Large area of (B-H curve).Alternate Answer
Soft iron has lower retentivity/Lower coercivity/Lower permeability/Smaller area of (B-H curve).

Substances, which at room temperature, retain their ferromagnetic property for a long period of time are called permanent magnets. Alnico, cobalt, steel and ticonal.

Zero.

Diamagnetic.Alternate Answer
Ferromagnetic.

Magnetisation is not easily erased by stray magnetic field/minor mechanical damage/temperature variation.

No we cannot have single pole magnet.A magnet always has two poles.

Energy density at center is greater than ends.
So as solenoid tries to reserve its energy at center thus it opposes any change in energy.

Current on its surface changes but no magnetic feild passes through it as magnetic field inside the copper box is zero.

Iron is a ferromagnetic substance while and copper is diamagnetic, the susceptibility of iron is much larger.

For an electromagnet, the substance should have high retentivity but low coercivity. Soft iron is such a substance.

The angle of dip at the magnetic poles of Earth is 90°.

Yes we can have magnetic potential scalar in this case.

No, in a magnetic dipole there are only two distinct poles that are at the ends.

The magnetic lines of force at the poles of Earth are vertical due to which the magnetic needle becomes vertical. the needle dips vertically.