Question

a) In the wave picture of light, what determines the following properties? i. Color of the light ii. Brightness/intensity of the light iii. Energy of the light

b) In the photon picture of light, what determines the following properties? i. Color of the light ii. Brightness/intensity of the light iii. Energy of the light

Answer 1

a) In the wave picture of light

i) wavelength determines the colour, different colours are due to different wavelengths.

ii)The intensity is the energy transferred through unit area in unit time, which is proportional to the amplitude of the wave. Therefore, intensity of the wave corresponds to the amplitude of wave

iii) Frequency of wave determines energy. Different frequencies corresponds to different energy.

b)In the photon picture of the light

i)The size of the particle determines the colour. In fact if we are using the word photon, the photon itself corresponds to the frequency and to the wavelengthfrom from which we can talk about the colour of light.

ii)Intensity of light is determined by number of photons. More the photons more is the intensity.

iii) Kinetic energy of the particle corresponds to the energy. Again i shall mention that if we are talking about energy of photon its energy can be given as, that means energy is determined by frequency itself.

Note: The first sentences in b)i) and b)iii) are about the newtons carspucular theory of light.