If we consider the light is particle then the energy equation is E = nh (new). Here n is number of the photon, (new) is frequency of the photon and h is minimum energy of the photon (Plank’s constant). However it is not clear to me how much the frequency of the white (compound) light?
White light is combined form of all visible lights and each light has its own frequency frequency.
If your question is about the using planks law then you have to select the frequency of all light in visible range and calculate the individual E and finally sum it.
Dr. Muhibullah, appart from your misconception concerning a frequency of compound light, which was commented on by Alok already, you seem to adhere to an even more bizarre misconception, namely that Planck's constant is a minimum energy of a photon. Do you think that frequency '1' (1 period per second ????) is a choice of nature ?
Light has the dual character. It is particle for the case of Compton Effect, Raman Effect, Photo electric effect, black body radiation etc. The light is wave for the case of interference, diffraction, polarization etc. I think two opposite type characters in parallel is not logical. Either quantum theory or electromagnetic wave theory is right.
However photon has momentum without mass, it is not logical. Another thing the particle shows wave nature as shown in De Broglie equation is not doubtless. Because the group velocity exceeds than the light velocity for the case of phase velocity is less than the light velocity which is impossible. We cannot consider any velocity of a thing (or energy) larger than light velocity.
According the Plank’s quantum theory the light energy is quantized. So, it is not to me clear that the frequency of the white (compound) light.
as per our measurement, in the room it is 250-500 Lux, outside when there is a bright sun 1000-1500 Lux. It differ at different time of the day. As Alok opined, it is a mixture of all visible light, highly depends on refractory index of the surface.
There is something wrong with your formula and there is no such thing as frequency of white (compound) light. The correct formula is E = h(new) which is Planck formula for each individual photon. White light is a wave packet of electromagnetic spectrum which includes all frequencies of individual seven colors. h is not minimum energy of photon.
Very interesting discussion.
The white light is a composite light which means that it is not a monochromatic light, i.e. not a single wavelength light. The white day light can be analyzed to its constituting components into multicolour light using glass prisms . It is found that the white light is composed of three basic colours; the red , the green and the blue with certain specific proportions. A mono chromatic light has certain photon energy, frequency and wave length.
Photons have energy and momentum. Photons can not be found in rest. That is there is no meaning to say that the rest mass of photons is zero. Electromagnetic fields are dynamic. It is mow a matter of fact that the photon have momentum.
The white light is not a monochromatic light and therefore we can not apply the Planck formula on it. But instead on its monochromatic components, the red , the blue and the green.
Thank you
@Abdellalim,
The monochromatic components of light are (different from what the word suggests) charactericed by a certain freqency and not by a certain color. Color is a phenomen which describes the interaction of radiation with the biological system 'human eye'. The physics of light does not know 'color'. Not all monochromatic radiations are either red, green, or blue. There is also yellow, for instance (notice that prior to the invention of the laser, the only easily accessible nearly 'monochromatic' light was the light of a flame into which a grain of salt was thrown, it was yellow). Also light which is clearly red may be composed of light of many well discernible frequencies.
Thank you Ulrich for your notice on my comment.
My vision is an electronic engineer understanding of the white light. White itself is a human sensation of a range of wavelengths of electromagnetic radiation ranging from red to blue. After your comment it can be said that monochromatic light is not a single wavelength source. This means that the color red covers a range of wavelength. It is the range of wavelengths seen by the eye and interpreted as RED and so on. But in general, there is a correspondence between the colour and wavelength. May be the definition of the colors at the corresponding wavelength more precised to narrow the range of the wavelength representing certain color. In this case one can consider that all photons int his range have a photon energy in the center of the color range.
Thank you very much Professor Dr. Abdelhalim Zekry for your very nice comments. I wish to reveal the limitation of Planck's Einstein law E = nh(new) by this question.
Dear Dr. Muhibbullah
Not at all. It is interesting discussions. A single photon is a packet of an electromagnetic wave which means it is confined in space and therefore behaves like particles. The energy of a single photon is known to be Eph= h (new) according to Max Planck. If a light source emits light at certain (new) wavelength, then the energy emitted from the source per second is E= n Eph = n h (new), where n is the number of photons of energy Eph emitted from the sources per second. So, the multiplicity of the photon energy is due to the multiplicity of the photon emission from the material. Practically n represents the intensity of the emitted light at the wavelength Labda= C/(new). So, a light at certain wavelength has an intensity and a new.
Wish you success.
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