In Young's double-slit experiment using monochromatic light of wavelength `lambda,` the intensity of light at a point on the screen where path difference is `lambda`, is K units. What is the intensity of lgight at a point where path difference is `lambda/3`.

Explanation

Let `I_1=I_2=I`, If `phi` is phase difference between the two light waves, then resultant intensity, `I_R=I_1+i_2 +2sqrt(I_1I_2). Cos phi`
When path difference `=lambda`, Phase difference `phi=0^(@), therefore I_(R)=I+I+2sqrt(II).cos 0^(@)=4I=k`
When path difference `=lambda/3`. phase difference `phi=(2pi)/(3) rad` `therefore I_R=I+I+2sqrt(II). cos""(2pi)/(3) Rightarrow I_R=2I+2I ((-1)/(2))=I=k/4`