106debo. ans 3 is correct. (i just wanted proofs)
Q2. edited
Q1. Assume that the light is monochromatic. Let the no. of photons falling on a surface per unit time be 'n' and I = intensity of light.. Then
I\propto n^x where x= _____
Q2. Change in phase when a longitudinal wave reflects off a surface = x while change in phase when a transverse wave reflects = y. Then (x+y)/2Ï€ = _____ (consider that the reflecting surfaces are perfectly rigid wrt the waves)
Q3. Consider a point source of light. Intensity (I) at a point situated at a distance R from the source is given as I= kRx then x = _____
Q4. Why doesnt the intensity depend on distance in a ydse like setup where one of the slits is closed?
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10 Answers
19for answer 2, what is to be known is that there is a phase change of ∩ when a longitudinal/transverse wave reflects from in interface which separates two mediums, the one in which the wave velocity is smaller being the one through which the wave is transmitted and the incident ray is travelling through the medium in which the wave velocity is larger ! just take the example of a light string and a heavy string joined together and the wave travels from the lighter to the heavier string !
for answer 3, intensity at a distance (r) due to a point source = I/ 4∩r2
intensity at a distance (r) due to a point source =I/4∩r
106debo, will the answer for (2) be valid even if it is a sound wave?
can u pls derive the exps for (3)?
19ans (2) yes, i think it should be the same !
ans (3)...feeling lazy to type [3]..i will get it soon !
106but in HCV while calculating path difference has ignored the phase differnce of π.. see solved eg.11 sound waves (pg 348)
14) coz the distance is too small for the fall in intensity
as i is inversely prop to r^2 and the typical distance in a ydse distance practical setup is 1m
11) u think it will be 1
as intensity is enrgy per unit surface area
and the enrgy by a group of phtons is prop to the number of the phtons strinking the surface