NTA Abhyas JEE Main2020PhysicsWaves and SoundPractice
Consider two coherent, monochromatic (wavelength λ ) sources, S 1 and S 2 , separated by a distance d . The ratio of intensities of S 1 and that of S 2 (which is responsible for interference at point P , where detector is located) is 4 . The distance of point P from S 1 is (if the resultant intensity at point P is equal to 9 4 times of intensity of S 1 ) (Given: ∠ S 2 S 1 P = 90 ° , d > 0 and n is a positive integer)
Options
- Ad 2 - n 2 λ 2 2 n λ
- Bd 2 + n 2 λ 2 2 n λ
- Cn λ d d 2 - n 2 λ 2
- D2 n λ d d 2 - n 2 λ 2
Correct answer
A. d 2 - n 2 λ 2 2 n λ
Step-by-step solution
9 4 intensity of S 1 = 9 times of intensity S 2 Intensity of maxima = I 1 + I 2 2 = 9 I 2 ⇒ S 2 P - S 1 P = n λ for maxima d 2 + x 2 - x = n λ         x = d 2 - n 2 λ 2 2 n λ