Question

Which coloured light bulb- red, orange, yellow, green, or blue- emits photons with (a) the least energy and (b) the greatest energy? Account for your answers.

Answer 1

Hint :In order to solve this question, we are going to first check the amount of the wavelength of the different colours as given above and hence, their frequencies and as we know that the energy of the emitted photons depend directly upon the frequency, thus, least and greatest energies can be determined.
Formula used: Frequency is given by the formula
 $ \nu = \dfrac{c}{\lambda } $
Energy is given by
 $ E = h\nu $

Complete Step By Step Answer:
The red colour of the light has the largest wavelength out of the colours given above. Now, as we know that the wavelength of light is inversely proportional to the frequency by the relation
 $ \nu = \dfrac{c}{\lambda } $
Hence, the red colour bulb has the lowest frequency. Now, the energy of the emitted photons is given by
 $ E = h\nu $
Thus, photons with least energy are emitted by the red colour.
Now, for the greatest energy, the colour of the bulb should be the one with the largest frequency hence the lowest wavelength, which is the blue coloured bulb. Hence, we can say that the blue- coloured bulb emits photons with the greatest energy.

Note :
The term VIBGYOR gives the notation for the colours that are dispersed from the white light. Where the Violet colour is the one with the least wavelength while the Red colour is with the largest wavelength. The violet colour emits photons with greatest energy and just after violet, there is blue colour, hence, it emits photons with the greatest energy.