A physical constant, also known as a basic physical constant or a universal constant, is a physical quantity that is universal in nature and has a constant value across time. A mathematical constant, on the other hand, has a fixed numerical value but does not entail any physical measurement.

The speed of light in vacuum c, the gravitational constant G, the Planck constant h, the electric constant ε₀ and the elementary charge e are some of the most well-known physical constants in science. The speed of light is a physical constant that denotes the greatest speed for any object, and its dimension is length divided by time.

Value of hc-

Now we will take a look at what is h, c and what is hc in physics.

h-

The Planck constant is the proportionality constant that connects the energy of a photon to its frequency. The constant is crucial in quantum physics because it serves as the foundation for the defining of the kilogramme unit of mass.

The symbol h represents Planck’s constant.

h = 6.62606896(33) x 10-34 J·sec
Because the value of the constant is determined by the units used to define it, it is known precisely in atomic units but only to 12 parts per billion in the metric system.

Max Planck’s successful attempt to construct a mathematical equation that precisely anticipated the observed spectrum distribution of heat radiation from a closed furnace resulted in the formulation of Planck’s constant (black-body radiation). Planck’s law is the name given to this mathematical equation.

Max Planck spent the latter years of the nineteenth century researching the subject of black-body radiation, which had been raised by Kirchhoff 40 years before. Every physical organism emits electromagnetic radiation on a constant basis. The overall form of the measured emission spectrum has no expression or explanation. 

Wien’s equation suited the facts for short wavelengths and high temperatures at the time, but it didn’t work for long wavelengths. Lord Rayleigh had devised a theoretical formula, now known as the Rayleigh–Jeans law, about this time, although Planck was unaware of it. It could fairly forecast long wavelengths but failed spectacularly at short wavelengths.

Planck proposed that the equations of motion for light describe a collection of harmonic oscillators, one for each potential frequency, as a solution to this dilemma. He tried to replicate Wien’s rule by looking at how the entropy of the oscillators changed with body temperature and he was able to develop an approximate mathematical function for the black-body spectrum, which yielded a simple empirical expression for long wavelengths.

Planck attempted to replicate Wien’s law (for short wavelengths) and the empirical formula using mathematics (for long wavelengths). A constant h was provided in this equation.

c-

The speed of light is defined as the speed at which a photon of light travels in vacuum. It is represented by the letter c and measured in SI units of m/s. The value of c or the velocity of light, is a constant everywhere in the cosmos. C= 299,792,458 m/s.

 The speed of light is regarded as a basic natural constant. Its relevance extends well beyond its function in characterising an electromagnetic wave characteristic. It is the universe’s sole limiting velocity, serving as an upper constraint on signal transmission speeds as well as the speeds of all material particles. The speed of light (c) acts as a proportionality constant in the famous relativity equation E = mc2, connecting the previously independent ideas of mass (m) and energy (E).

What is hc in physics-

The existence of Planck’s constant, h = 6.62606896(33) x 10-34 J·sec
, in an issue indicating that it belongs to the quantum physics category. Photons, the particle like component of electromagnetic waves, and the de Broglie wavelength, the wavelike property assigned to particles in quantum mechanics, are both associated with Planck’s constant.

 A photon is a packet of electromagnetic energy that looks like a particle. A photon’s energy E is equal to hv = hc/λ, where v is the electromagnetic radiation’s frequency and c is the wavelength. In quantum physics, energies are usually measured in electron volts (1 eV = 1.6 109 J) while wavelengths are measured in nanometers (1 nm = 10-9 m). A useful connection between photon energy E in eV and radiation wavelength in nm is widely used to simplify quantum calculations: E(eV) =1.24 × 103/λ(nm). A photon with wavelength carries linear momentum of magnitude p = h/λ despite the fact that it has no mass. This momentum, or a portion of it, may be transmitted to particles that collide with photons.

Photoelectrons are emitted from a metal surface when a sufficiently high frequency light is shown onto it. The photoelectric effect is the name for this phenomenon.

hν=W+E –formula 

hc = 1.23984193×10-6 eV.m, value of hc.

Conclusion-

In this article we read about what we mean by h, c, value of hc and photoelectric effect. Scientists now utilise Planck’s constant to calculate total energy by multiplying it by the frequency of a wave (E=hf). This is significant since Planck’s constant is the fundamental constant of quantum physics. It describes how the cosmos allows life to exist in any form.

The speed of light is another universal constant that you may be acquainted with. Planck’s constant is also significant since it aided in the development of quantum physics, which is critical to human knowledge of star evolution. Planck’s constant advanced our understanding of atoms and matter, paving the way for the development of integrated circuits, transistors, and even electronic chips, all of which are essential components of contemporary electronics.