Question

Young double slit experiment is performed in a liquid and it is observed that 10th bright fringe in liquid lies where 6th dark fringe lies in vacuum

Answer 1

Hello guys Namaste,

Question:- Young double slit experiment is performed in a liquid and it is observed that 10th bright fringe in liquid lies where 6th dark fringe lies in vacuum.

Answer:- Why do we not ordinarily observe wave behavior for light, such as observed in Young’s double slit experiment? First, light must interact with something small, such as the closely spaced slits used by Young, to show pronounced wave effects. Furthermore, Young first passed light from a single source (the Sun) through a single slit to make the light somewhat coherent. By coherent, we mean waves are in phase or have a definite phase relationship. Incoherent means the waves have random phase relationships. Why did Young then pass the light through a double slit? The answer to this question is that two slits provide two coherent light sources that then interfere constructively or destructively. Young used sunlight, where each wavelength forms its own pattern, making the effect more difficult to see. We illustrate the double slit experiment with monochromatic (single λ) light to clarify the effect. The pure constructive and destructive interference of two waves having the same wavelength and amplitude.

The peaks and troughs of each wave are aligned with those of the other waves. The top two waves are labeled wave one and wave two and the bottom wave is labeled resultant. The amplitude of waves one and two are labeled x and the amplitude of the resultant wave is labeled two x. except that the peaks of wave two now align with the troughs of wave one. The amplitudes of waves add. Pure constructive interference is obtained when identical waves are in phase. Pure destructive interference occurs when identical waves are exactly out of phase, or shifted by half a wavelength.

Pure constructive interference occurs where the waves are crest to crest or trough to trough. Pure destructive interference occurs where they are crest to trough. The light must fall on a screen and be scattered into our eyes for us to see the pattern. Note that regions of constructive and destructive interference move out from the slits at well-defined angles to the original beam. These angles depend on wavelength and the distance between the slits, as we shall see below.