Electricity

• These waves are transverse and neutral.
• In this, the electric field and the magnetic field oscillate perpendicular to each other and the direction of propagation of the waves is perpendicular to the electric and magnetic field.

Hence, except for option (a), all the other options are correct.

• EMF is the commonly used acronym for electromotive force.
• The work done to make a unit charge flow in opposition, that is, the value of the energy expended by the electric cell is called the electromotive force,

• For example, silver is the good conductor of electricity.
• Graphite is a good conductor of electricity, depending on the options.

Electrical Conductivity

• Definition:
  Electrical conductivity is a measure of a material’s ability to allow the flow of electric current through it.

• The metal which is used as a cathode to produce a photoelectric effect should have a high melting point and low work function.

Hence, the required answer would be options (a) and (c).

• Therefore, mercury is the only conducting material among them.
• All the rest are insulators of electricity.

• Diamond does not conduct electricity because it has no free electrons.

Here's a more detailed explanation:

1. Structure of Diamond: In a diamond, each carbon atom is covalently bonded to four other carbon atoms in a strong, three-dimensional tetrahedral network. All four valence electrons of each carbon atom are involved in forming these strong covalent bonds.
2. Absence of Free Electrons: Because all the valence electrons are tightly held in these bonds, there are no electrons that are free to move throughout the crystal lattice.
3. Electrical Conductivity: Electrical conductivity in a material depends on the presence of mobile charge carriers, which are usually free electrons. Since diamond lacks these free electrons, it cannot conduct electricity. It acts as an excellent electrical insulator.

In contrast, graphite, another allotrope of carbon, has a layered structure where each carbon atom is bonded to only three other carbon atoms. This leaves one valence electron per carbon atom delocalized and free to move between the layers, allowing graphite to conduct electricity.

• That's why it is called the anti-particle of the electron.
• Its spin is 1/2.

• In this process, when waves of light are thrown onto a suitable electron-emitting metal surface, the light is treated as photon particles containing bundles of energy.
• These photons are capable of emitting electrons from the orbitals (energy levels) of the metallic atom.