Nonreflective Film: Solving the Ref. Index Problem

AI Thread Summary
The discussion focuses on addressing the refractive index problem in nonreflective films by sandwiching the coating between lens surfaces. It highlights the conditions for destructive interference occurring at both the front and back surfaces of the lens, emphasizing that the equations governing these conditions may differ due to potential phase differences upon reflection. The speaker expresses a desire to rederive the necessary equations independently rather than relying on existing resources. Additionally, the conversation notes that four rays must emerge from the lens to achieve the desired destructive interference. Understanding these principles is crucial for effectively designing nonreflective coatings.
Andy1011
Messages
1
Reaction score
0
Homework Statement
A glass lens of index 1.5630 is to be nonreflecting on both surfaces. What should be the refractive index and thickness of the coating for a light of 5500 A to produce 0 reflactance?
Relevant Equations
2nd = m lambda
2nd = (2m+1)lambda/2
I thought of sandwiching the coating between lens sufaces and then applied the condition of minimum which gave a thickness of lambda/2*ref. Index and I got totally stuck at the ref. Index.
 
Physics news on Phys.org
There are two conditions of destructive interference, one at the front surface and one at the back surface. The equaitons describing the conditions are not necessarily the same because of the phase difference that may or may not be there upon reflection. I would rederive them for myself instead of looking them up. There are four rays emerging from the lens that have to interfere destructively

Front surface
Path 1 air⇒coating; Path 2: coating⇒glass
Back surface
Path 1 coating⇒glass; Path 2: glass⇒air
 
Thread 'Voltmeter readings for this circuit with switches'
TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
Thread 'Correct statement about a reservoir with an outlet pipe'
The answer to this question is statements (ii) and (iv) are correct. (i) This is FALSE because the speed of water in the tap is greater than speed at the water surface (ii) I don't even understand this statement. What does the "seal" part have to do with water flowing out? Won't the water still flow out through the tap until the tank is empty whether the reservoir is sealed or not? (iii) In my opinion, this statement would be correct. Increasing the gravitational potential energy of the...
Back
Top