What is h in E HF?

Q: What is H in Plancks equation?

Plancks constant, symbolized as h, is a fundamental universal constant that defines the quantum nature of energy and relates the energy of a photon to its frequency. In the International System of Units (SI), the constant value is 6.62607015×10−34 joule-hertz−1 (or joule-seconds).

Q: What is H in quantum theory?

Plancks constant, (symbol h), fundamental physical constant characteristic of the mathematical formulations of quantum mechanics, which describes the behaviour of particles and waves on the atomic scale, including the particle aspect of light.

That's very interesting, thanks. Although I have to admit I don't totally follow you. I haven't really learned quantum physics in depth yet as I'm only at A-Level level (high school). But it's clarifying in a really paradoxical way because I thought there was something really obvious I'm missing but now I see there's a lot more to it than what I've been learning about which is probably really superficial.
If you wouldn't mind just one more question: is Planck's constant just something that makes the equation work or is it something deeper than that?

Table of Contents Show

Spectral forms[edit]
de Broglie relation[edit]
Bohr's frequency condition[edit]
What is the value of H in E HF?
What is H in Planck's equation?
What is H in quantum theory?
What does E in E hf mean?

Daniel Wqw said:
Thankyou very much.
However I have to say that I'm still confused about the fact that in order for the E=hf equation to work you have to assume light is a stream of particles however you also assume light is a wave for you to measure the frequency.

You don't have to assume that it is a stream of particles. Think about it as a wave that delivers its energy to its target in an odd and surprising way.

And what do you mean by light isn't a stream of particles in the sense that raindrops are a stream of particles?
Thanks.

I mean exactly that. When people first hear that photons are "particles" of light, the mental image that forms is a little tiny bullet (if it's moving fast) or grain of sand (not moving so fast) or other small object traveling through space. That picture is hopelessly misleading, as a photon has neither a position nor a path except at the moment that it interacts with something else.

If you can get hold of Richard Feynman's book "QED: The strange theory of light and matter", I highly recommend it... No advanced math required.

Nugatory said:
You don't have to assume that it is a stream of particles. Think about it as a wave that delivers its energy to its target in an odd and surprising way.

I mean exactly that. When people first hear that photons are "particles" of light, the mental image that forms is a little tiny bullet (if it's moving fast) or grain of sand (not moving so fast) or other small object traveling through space. That picture is hopelessly misleading, as a photon has neither a position nor a path except at the moment that it interacts with something else.

If you can get hold of Richard Feynman's book "QED: The strange theory of light and matter", I highly recommend it... No advanced math required.

Wow I feel brainwashed. I've always thought of the photons as particles in the sense of a bullet. I've even seen documentaries talking about photons with animations of yellow spheres gliding through the air. To be honest I'm doubtful of the truth of most of the things I'm learning in my A-Level quantum physics course because it all seems so oversimplified and shallow. I think I should wait for Physics at University for the accurate picture. Or in the meantime read QED :)

The Planck relation (referred to as Planck's energy–frequency relation, the Planck relation, Planck equation, and Planck formula, though the latter might also refer to Planck's law) is a fundamental equation in quantum mechanics which states that the energy of a photon, E, known as photon energy, is proportional to its frequency, ν:

E=hν{\displaystyle E=h\nu }

The constant of proportionality, h, is known as the Planck constant. Several equivalent forms of the relation exist, including in terms of angular frequency, ω:

E=ℏω{\displaystyle E=\hbar \omega }

where ℏ=h/2π{\displaystyle \hbar =h/2\pi }. The relation accounts for the quantized nature of light and plays a key role in understanding phenomena such as the photoelectric effect and black-body radiation (where the related Planck postulate can be used to derive Planck's law).

Spectral forms[edit]

Light can be characterized using several spectral quantities, such as frequency ν, wavelength λ, wavenumber ν~{\displaystyle \scriptstyle {\tilde {\nu }}}, and their angular equivalents (angular frequency ω, angular wavelength y, and angular wavenumber k). These quantities are related through

ν=cλ=cν~=ω2π=c2πy=ck2π,{\displaystyle \nu ={\frac {c}{\lambda }}=c{\tilde {\nu }}={\frac {\omega }{2\pi }}={\frac {c}{2\pi y}}={\frac {ck}{2\pi }},}

so the Planck relation can take the following 'standard' forms

E=hν=hcλ=hcν~,{\displaystyle E=h\nu ={\frac {hc}{\lambda }}=hc{\tilde {\nu }},}

as well as the following 'angular' forms,

E=ℏω=ℏcy=ℏck.{\displaystyle E=\hbar \omega ={\frac {\hbar c}{y}}=\hbar ck.}

The standard forms make use of the Planck constant h. The angular forms make use of the reduced Planck constant ħ = h/2π. Here c is the speed of light.

de Broglie relation[edit]

The de Broglie relation, also known as the de Broglie's momentum–wavelength relation, generalizes the Planck relation to matter waves. Louis de Broglie argued that if particles had a wave nature, the relation E = hν would also apply to them, and postulated that particles would have a wavelength equal to λ = h/p. Combining de Broglie's postulate with the Planck–Einstein relation leads to

p=hν~{\displaystyle p=h{\tilde {\nu }}}

p=ℏk.{\displaystyle p=\hbar k.}

The de Broglie's relation is also often encountered in vector form

p=ℏk,{\displaystyle \mathbf {p} =\hbar \mathbf {k} ,}

where p is the momentum vector, and k is the angular wave vector.

Bohr's frequency condition[edit]

Bohr's frequency condition states that the frequency of a photon absorbed or emitted during an electronic transition is related to the energy difference (ΔE) between the two energy levels involved in the transition:

What is the value of H in E HF?

Here, E stands for energy in a photon. f stands for the frequency of light. and h stands for Planck's constant and This 'h' the Planck's constant has a fixed value of about $h = 6.62 \times {10^{ - 34}}J\sec $ which has a unit of Joule seconds.

What is H in Planck's equation?

Planck's constant, symbolized as h, is a fundamental universal constant that defines the quantum nature of energy and relates the energy of a photon to its frequency. In the International System of Units (SI), the constant value is 6.62607015×10⁻³⁴ joule-hertz⁻¹ (or joule-seconds).

What is H in quantum theory?

Planck's constant, (symbol h), fundamental physical constant characteristic of the mathematical formulations of quantum mechanics, which describes the behaviour of particles and waves on the atomic scale, including the particle aspect of light.

What does E in E hf mean?

The equation, E=hf, is referred to as the Planck relation or the Planck-Einstein relation. The letter h is named after Planck, as Planck's constant. Energy (E) is related to this constant h, and to the frequency (f) of the electromagnetic wave.