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Light Waves and Color

The visible light is emitted and absorbed by tiny packets called photons and exhibit properties of both waves and particles. This property is known as wave-particle duality.

Light waves can be measured in two different ways,

  •    Amplitude of the wave
  •    Frequency of the wave along with the number of waves per second.

These waves are categorized according to the frequencies that have similar characteristics in the electromagnetic spectrum of the light. The subcategories of each spectrum vary according to the wave frequency.

The color of these lights depends on the reflection quality from the objects on which the white light falls on. For example, the white wall appears because the wall reflects back all the colors.  

Any particular color that looks from any surface is the color that is reflected from the object when the light falls on it.

The light wave and color formula is given by:

 c = ν  x λ


c = speed of light

v = frequency

λ= wavelength

Example 1

Calculate the frequency of the violet color whose wavelength is 400 nm.


Given: Wavelength = 400 nm

We know that, C (Speed of Light ) = ν (Frequency ) × λ ( Wavelength)

ν = C / λ

 = 3×108  / 4.00×107

Therefore, frequency = 7.5 Hz

Example 2:

Determine the wavelength and predict the color of light which has a frequency of 6.00 × 1014 Hz, given the speed of light is 3 × 108 m / s.


Given: Frequency = 6.00 x 1014 Hz

We know that, C (speed of light ) = ν (frequency ) × λ ( wavelength)

λ = C / ν

 = 3×108 / 6.00 × 1014

Therefore, λ (wavelength) = 0.5 × 10 -6

                = 5000 × 10-9 m

                = 5000 nm

The color of the wavelength of 5000 nm is green.