## Site blog

Academic transcript for the Graduands / Graduates of the Faculty of Applied Sciences will be issued from 11^{th} June 2020.

Applicants are kindly requested to fill the Application Form (* Download Application Form) *to obtain the academic transcript. University will charge Rs. 100/= per this certificate for handing over to the applicant. (Rs. 100/= per each additional). Payments should be credited to the Account No: 097 -1001-6-2315454 people’s bank, Gangodawila, Nugegoda, Sri Lanka and forward the scanned copy of the Bank Receipt and the filled Application Form through exams@sjp.ac.lk

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An e-mail message will be forwarded to the Graduands/Graduates after processing the transcript and the transcript can be collected at the Main Gate of the university by producing original of the Application Form and the original copy of Bank Receipt.

If Graduands/Graduates need to send this certificate to a Local or Foreign Institute, Rs.250/- or Rs.500/- will be charged respectively and duly filled Application Form and Bank Receipt should forward to the Examinations Division.

**Download Application Form for Academic Transcript**

**Senior Assistant Registrar**

Examinations Division

Tel : **0112758219**

### Comments

1) why Compensator is placed inclinedly.

*Compensator is placed at a 45 degree angle so that it is parallel to the beam splitter. Compensator is identical to the beam splitter except for the silver coating, The path length through each of these components is equal only if they are placed parallel to one another.*

2)can we use Compensator vertically as shown in figure.(figure is attached to this mail)

__ __*No. Then the path length through each component will not be the same.*

Madam this your exercise for the note

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Exercise: Suppose that the fringe order of the central dark fringe is 100. If you move away from the center, what are the orders of the next three consecutive rings of the fringe pattern? (Hint: Consider the variation of the angle corresponding to fringes as you move away from the center).

__Madam I can not understand problem. __

3)Could you please help me to understand this problem.

Please give me answer for this problem.

*The next 3 orders would be 99, 98 and 97. I just wanted to draw students’ attention to the fact that the fringe order decreases away from the center in the circular fringes obtained from the Michelson Interferometer. (Compare with Newton rings and note the difference.)*

A picture was attached to this mail. It is part of your note of the Michelson Interferometer.

If the fringe orders for the D1 and D2 lines at the start are N1 and N2 respectively, the fringe orders for the two lines , N1’ and N2’ are given by,

N’=N2+N (1)

N1’=N1+N+1 (2)

madam, I can not understand how was the second equation constructed.

I think I will ask you to do a small exercise to understand this point. Take a graph paper and first draw a wave of wavelength 10 mm. Now draw another wave of wavelength 12 mm on top of the first wave. Initially they should be in phase so that the maxima coincide. As the waves progress you will notice a displacement between the 2 waves and at some point they will be out of phase. Going on further, at some point they will be in-phase again. When this happens count the number of wavelengths between the first in-phase position that you started with and the last in phase position for each wave. This exercise will shed light in understanding your problem.

This is what happens in the Michelson Interferometer when you adjust the screw gradually. Between two adjacent in-phase positions one of the two wavelengths will have traveled one additional wavelength than the other.

Thank you very much madam.

After plotting the graphs I have better idea what’s happening in the Michelson Interferometer.

Now I can understand.

Thank you very much again madam.