Question

What is the advantage of choosing the wavelength of light as a standard of length?
$1)$ Travels fast
$2)$ Speed independent of location and temperature
$3)$ No medium to travel
$4)$ No advantage

Answer 1

We know that light is electromagnetic radiation occurring within a specific portion of the electromagnetic spectrum. Light represents the visible part of the electromagnetic spectrum usually. It is distinguishable to human naked eyes and is responsible for the sense of sight. We need to discuss why the wavelength of light can be used as a standard of length.

Complete step by step solution:
Light can be defined as the electromagnetic radiation of a certain wavelength. It generally denotes the visible part of the spectrum. Radiations like gamma rays, radio rays etc. are all forms of light. Light exhibits dual nature both particle and wave nature. Light exists as a particle and it propagates as a wave. The particle nature of light consists of photons whereas the wave nature of light is the form of energy.
The fundamental unit of length which is metres is defined in terms of wavelength because the wavelength is accurately defined, invariable and it is not affected by changes in time or place or physical conditions like temperature and it is reproducible in laboratories. It also increases the accuracy of the measurement of length.
Therefore, option (2) is the correct option.

Note: Note that light waves are transverse, that is the oscillation in the wave is perpendicular to the direction of propagation of the wave. Wavelength is the distance between two consecutive crests or two consecutive troughs in a transverse wave. Crests and troughs are the maximum and minimum point of displacements respectively. Wavelength also represents the repeating pattern of any travelling energies like sound or light.