Why do we get straight line fringes in air wedge experiment?
The shape of the fringe depends on how the thickness of the air film enclosed varies. 2.In wedge shaped film the thickness of the air is constant over a straight line along the width of the wedge. 3. Hence the fringes are straight.
What is air wedge method?
An air wedge interferometer consists of two optical glass wedges (~2-5 degrees), pushed together and then slightly separated from one side to create a thin air-gap wedge. The air gap between the two glass plates has two unique properties: it is very thin (micrometer scale) and has perfect flatness.
How do you find the width of a fringe in an air wedge experiment?
The distance between any two consecutive bright or dark bands is called fringe width. When the crests or troughs of two interfering waves meet, constructive interferences are formed. When the crest of one wave meets the trough of another wave, destructive interferences are formed.
How do you find the fringe width of an air wedge experiment?
- Consider a point A very near to edge of the wedge such that thickness of the film at A is t1.
- t1 = λ/4μ t3 = 3λ/4μ
- t3 – t1 = λ/2μ
- tan ѳ = t3 – t1 /ꞵ
- Similarly, for dark bands 2 μ t2 = 2λ/2 i.e t2 = λ/4μ
- 2 μ t4 = 4λ/2 i.e t4 = λ/μ
- tan ѳ = (t4 – t2) /ꞵ
How many bright fringes are observed in an air wedge experiment?
An air wedge is formed between two thick glass n = 1:5 plates in con- tact along one edge and slightly separated at the opposite edge. When illuminated with monochromatic light from above, the reflected light re- veals a total of 85 dark fringes.
How can the thickness of insulation on a wire be measured by forming air wedge?
In manufacturing the wire, there will be some variation in insulation thickness along the length of the wire. Lets say this variation is 0.4 mm. So, if a minimum insulation thickness of 0.1 mm is needed for 2000V, then the insulation needs to be 0.5mm nominal thickness so it is never less than 0.1mm anywhere.
When two waves of the same amplitude add constructively the intensity becomes?
When the incoming light waves superimpose constructively, the intensity increases while when they add destructively, it decreases. Explanation: As we know, I ∝ A2. Thus, as the two waves add constructively, their amplitude becomes twice and hence the intensity becomes four times.