Physic Tutorials

Light of Different Colors In A Vacuum Travel At The Same Speed [Explained]

Electromagnetic waves are waves that do not require a material medium for their propagation i.e. they travel in a vacuum. Visible or white light is an example of electromagnetic waves. These waves are categorized according to their frequency f and wavelength λ = c/f


Light of different colors in a vacuum travels at 3 x 108 ms-1 i.e. they all travel at the same speed.

White light is a mixture of many different colors, each with a different frequency. White light can be split up into a spectrum of these colors using a prism and this process is called dispersion.


The seven colors of the spectrum are listed in order of their frequency i.e. lowest to the highest frequency – ROYGBIV

  • R – Red
  • – Orange
  • Y – Yellow
  • G – Green
  • B – Blue
  • I – Indigo
  • V – Violet

To evaluate the speed of light, the wavelength of each light is multiplied by its frequency

Wavelengths Of Visible light

  • Violet: 380–450 nm
  • Blue: 450–495 nm
  • Green: 495–570 nm
  • Yellow: 570–590 nm
  • Orange: 590–620 nm
  • Red: 620–750 nm

Frequency of Visible light

  • Red: 4.62 x 1014 Hz          
  • Orange: 5.00 x 1014 Hz   
  • Yellow: 5.16 x 1014 Hz    
  • Green: 5.45 x 1014 Hz     
  • Cyan: 5.99 x 1014 Hz        
  • Blue: 6.66  x 1014 Hz       
  • Violet: 7.50 x 1014 Hz

Using C = f λ , different colors of light above will give approximately 3 x 108 ms-1 in a vacuum. This implies that speed is constant irrespective of the differences in wavelength and frequency.

Read: Note on primary and secondary colours

Bolarinwa Olajire

A tutor with a demonstrated history of working in the education industry. Skilled in analytical skills. Strong education professional with a M. SC focused in condensed matter. You can follow me on Twitter by clicking on the icon below to ask questions.

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