Question

What is the name of ‘h’ and what is the value?

Answer 1

Hint: Max Planck’s quantum theory explains the photoelectric effect. Based on Planck’s quantum theory, light is emitted in the form of discrete packets of energy called ‘quanta’. The energy of each photon is E=h$\nu$. Where ‘h’ is called the Planck’s constant.

Complete step by step answer:
Planck’s constant is mostly used with photons, electromagnetic waves and also with de Broglie wavelength attributed to quantum physics. A photon is a packet of electromagnetic energy. It is also referred to as quanta. The energy of photon is given by,

$E=h\nu ={\displaystyle \frac{hc}{\lambda }}$

Where, ν is the frequency of the electromagnetic radiation
λ is the wavelength of the radiation and
h is the Planck’s constant

The value of Planck’s constant is $6.62607004\times {10}^{-34}Js$ .

The energies in physics are mostly expressed in electron volts and wavelengths are expressed in nanometers. $1eV=1.6\times {10}^{-9}J$ and $1nm={10}^{9}m$.

The relationship between the energy and radiation can be given by, $E={\displaystyle \frac{1.24\times {10}^3}{\lambda }}$.

A photon has no mass but it does have a linear momentum of magnitude ‘p’. The momentum can be transferred to other particles when they get to collide with photons. When high frequency lights are incident on a metal surface, it emits photoelectrons. This is called the photoelectric effect.

Note: The value of ‘h’ can also be given in cgs or small metric systems as $6.62607004\times {10}^{-27}$ erg-seconds. To measure Planck's constant, scientists have used two methods. They are the Kibble balance method and X-ray crystal density method. Both the methods gave similar results.