Question

Four monochromatic and coherent sources of light, emitting waves in phase of wavelength l are placed at the point x = 0, d, 2d and 3d on the x-axis. Then _

• A. Points having | x | >> d appear dark if d = $\frac{\lambda}{4}$
• B. Points having |x| >>d appear dark if d =$\frac{\lambda}{8}$
• C. Points having |x | >>d appear bright if d =$\frac{\lambda}{4}$
• D. Points having |x | >>d appear bright if d =$\frac{\lambda}{8}$

Answer 1

Answer: (A)

Points having | x | >> d appear dark if d = $\frac{\lambda}{4}$

Answer 2

For phase difference $\frac{\pi}{2}$ or d = $\frac{\lambda}{4}$

I_Resultant = 0