question_answer 14)

Let us list some of the factors, which couldpossibly influence the speed of wavepropagation: (i) nature of the source, (ii) direction ofpropagation, (iii) motion of the source and/or observer. (iv)wavelength, (v) intensity of the wave. On which of these factors, if any, doesthe speed of light in vacuum, (b) the speedof light in a medium (say, glass or water),depend ?  

Answer:

(a) Speed of light in vacuum is an absoluteconstant (universal constant). It isindependent of any factor. It is independentof the relative motion between source andobserver even. (b)(i) Speed of light in a medium dependsupon wavelength. («) It is independent of the nature of the source and motion ofthe source relative to the medium, (iii) Itdepends upon the properties of themedium of propagation and motion of theobserver relative to the medium, (iv) It isindependent of the direction of propagationfor isotropic medium, (v) It is independentof the intensity of the wave