Electric field intensity is a vector quantity as we need direction as well as magnitude to express it . It is often referred to as electric field or sometimes only field . So that’s the reason electric field is vector .

Reference

The concept is simple. A wave is characterized by its wavelength (λ), the distance between two corresponding points or successive peaks. The wavenumber (k) is simply the reciprocal of the wavelength, given by the expression. k = 1 / λ The wavenumber (k) is therefore the number of waves or cycles per unit distance.

K, in physics, refers to the Boltzmann constant which is a pyhsical constant that relates the average relative kinetic energy (Ek) of particles in a gas with the temperature (T) of the gas. It is 1.380649×10^-23 J⋅K^-1, where J is the symbol of energy and K is the symbol for temperature (in degrees Kelvin)

Boltzmann constant, (symbol k), a fundamental constant of physics occurring in nearly every statistical formulation of both classical and quantum physics.

constant of variation

Kinetic energy is sometimes represented by the letter T. This probably comes from the French travail mécanique (mechanical work) or quantité de travail (quantity of work).

There are five types of kinetic energy: radiant, thermal, sound, electrical and mechanical. Let us look at some of the kinetic energy examples and learn more about the different types of kinetic energy.

The symbol is used in physics for potential energy, for kinetic energy, for mass, for speed, for gravitational acceleration and for height.