Value of Planck's Constant

We have known many physical constants in physics. Planck’s constant is one such physical constant which defines the behaviour of particles and waves on the atomic scale along with the particle aspect of light. In this article, let us learn in detail about the Planck’s constant along with the value and applications.

Table of Contents

What Is Planck’s Constant?

In the quantum of electromagnetism, Planck’s constant is the physical constant that relates the energy carried by a single photon to its corresponding frequency. Represented by h and measure using J.s in the SI system and eV.s in the MKS system. The value of Planck’s constant has got prime importance in quantum mechanics. Therefore, Planck’s constant can be defined as,

A fundamental constant, equal to the energy of a quantum of electromagnetic radiation divided by its frequency.

What Is the Value of Planck’s Constant?

The value of Planck’s Constant or value of h is experimentally validated. The value of h is given below:

Value of h In SI units
= 6.6260715×10-34 J.s
Value of h In Meter-Kilogram-Second(MKS) units
h = 4.135667662×10-15 eV.s
Value of h in terms of Ep.tp
2 pi

Application of Planck’s Constant

The value of Planck constant is used in various applications including Planck’s equation. For example, the energy associated with a photon is given by the product of the Planck constant(h) and its frequency.

Plank Constant is the inseparable part of some revolutionary formulas. The list below gives a brief insight into it:

  • In Black body radiation, the spectral radiance of a body is given by:
\(\begin{array}{l}B_{\nu }\left ( \nu ,T \right )=\frac{2h\nu ^{3}}{c^{2}}\frac{1}{e^{\frac{h\nu }{k_{B}T}}-1}\end{array} \)
  • In the photoelectric effect, the famous Planck Einstein relation is given by:
\(\begin{array}{l}E=hf\end{array} \)
  • In atomic structure, Energy of nth orbit is given by:
\(\begin{array}{l}E_{n}=-\frac{hc_{0}R_{\infty }}{n^{2}}\end{array} \)
  • In uncertainty principle, the relation between position and momentum is given by:
\(\begin{array}{l}\Delta x\Delta p\geq \frac{\left ( \frac{h}{2\pi } \right )}{2}\end{array} \)
\(\begin{array}{l}\lambda =\frac{h}{p}\end{array} \)

Hope you got to know the value of Planck’s constant or value of h along with the formula, units, and its significance and applications in various parts of physics.

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Frequently Asked Questions – FAQs

Q1

What is the dimensional formula of Planck’s constant?

The dimensional formula of Planck’s constant is ML2T-1.

Q2

What is the use of Planck’s constant?

Planck’s constant is used for describing the behaviour of particles and waves at an atomic scale. Planck’s constant is one of the reasons for the development of quantum mechanics.

Q3

What is Planck’s law?

Planck’s law states that the energy of electromagnetic radiation is confined to quanta which cannot be divided and has an energy equal to the product of Planck constant and frequency of the radiation.

Q4

Why is LED used to determine Planck’s constant?

LED is used for determining Planck’s constant because the colour of LED has a different threshold voltage which produces electrons at a different voltage. This voltage along with the emission wavelengths can be used for determining the value of Planck’s constant.

Q5

Why do we use Planck’s constant?

We use Planck’s constant for measuring Planck length and Planck time.

Does light behave like a wave?

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