Magnetism | MCQs

Explanation

Magnetic flux linked (Φ) is proportional to the number of turns in the coil.

Doubling the number of turns doubles the total flux linked, assuming the magnetic field and area remain the same.

Explanation

Two parallel conductors carrying current in the same direction attract each other due to magnetic fields they produce.

If currents flow in opposite directions, the force would be repulsive.

Explanation

Magnetic induction 𝐵 represents the amount of magnetic flux passing per unit area — hence called magnetic flux density.

It is measured in tesla (T) in the SI system.

Explanation

The magnetic materials include cobalt, iron, and nickel.

Plastic cannot be magnetized nor can it be attracted to a magnet.

Explanation

Boiling a magnet (especially in water) does not generate enough heat to affect its magnetic properties.

In contrast, hammering, heating, or dropping disturb the alignment of magnetic domains, leading to demagnetization.

Explanation

Iron magnets are temporary because they lose magnetism quickly when the external magnetic field is removed.

Steel magnets retain their magnetism for a long time, making them permanent magnets.

Explanation

O₂ (oxygen molecule) is paramagnetic because it has unpaired electrons in its molecular orbitals.

According to Molecular Orbital Theory (MOT), the electronic configuration of O₂ reveals 

There are two unpaired electrons in the π* anti-bonding orbitals, which are responsible for its paramagnetic properties.

Hybridization and resonance do not directly explain the presence of unpaired electrons in this context.

Explanation

In the complex  [ 𝐹 𝑒 ( 𝑁 𝐻 3 ) 6 ] ^2 + , iron (Fe) is in the +2 oxidation state, meaning it has a  𝑑6 electron configuration.

Ammonia (NH₃) is considered a strong field ligand under Crystal Field Theory (CFT), causing the electrons in the 𝑑-orbitals to pair up due to the large splitting of the 

𝑑-orbitals.

In a strong field environment, the electrons occupy the lower energy  𝑡2𝑔 orbitals first, and all six electrons pair up, leaving no unpaired electrons.

Therefore, the number of unpaired electrons is 0.

Explanation

The direction of the magnetic field lines inside a bar magnet is from south pole to north pole.

This is the opposite direction of the field lines outside the magnet, which go from the north pole to the south pole.

Explanation

The Earth's South Magnetic Pole is geographically north, and the Earth's magnetic North Pole is geographically south, so free-moving magnets are always north-south.