Which of the following properties of laser beam can be used to measure long distances?

Options

A. Yellow light is scrattered more by the fog particles
B. Yellow light is scrattered more by the fog particles
C. Yellow light is unaffected during its passage through the fog
D. Wavelength of yellow light is the mean of the visible part of the spectrum

Explanation

Sodium lamp light emits monochromatic light i.e. it is comprised of only one wavelength(deep yellow).This colour is scattered less in the foggy codition while other light sources produce light at many different discrete wavelengths and all provide some degree of colour rendering.Also sodium lamps emit light very near to the peak sensitivity of the human eye under normal viewing coditions.