# Wave optics

Confused over option 2 and 3 kindly see

And 2nd i am not getting all correct options so see this one too.

I used path difference due to reflection on mirror and direct path in second to get some relation but was not able to eliminate many variables , need simpler approach i guess.

Answer for question number 4 is option 2 and 3??

INCORRECT its not 2 and 4

I am telling the answer for the question in 2nd image the mirror oneâ€¦

And i said it should be 2 and 3â€¦

Sorry my mistake

Thats correct how did u get it ? I tried but didnt got

Instead of considering phase difference from reflection etc etcâ€¦

You can consider 2 sources, one is the original source S and one will be its image in the mirrorâ€¦

And treat this a normal YDSE experimentâ€¦

And fringe width will be the same as in YDSE, the only difference will be its slit/ source separationâ€¦

See the image attached to understand the differenceâ€¦

Initially take 2d and as per the question they shift the source by 0.6mm then take it as 2(d+0.6)â€¦ Like this you get 2 equationsâ€¦ And 2 variablesâ€¦ Lambda and dâ€¦ Solve for dâ€¦ You get the initial distance from A where source is keptâ€¦ Now using any 1 equation find lambdaâ€¦

Thanks a lot , my method was very wrong

Try 1st one too