Two coherent sources of sound, S₁ and S₂, produce sound waves of the same wavelength, $$\lambda $$ = 1 m, in phase. S₁ and S₂ are placed 1.5 m apart (see fig). A listener, located at L, directly in front of S₂ finds that the intensity is at a minimum
when he is 2 m away from S₂. The listener moves away from S₁, keeping his distance from S₂ fixed. The adjacent maximum of intensity is observed when the listener is at a distance d from S₁. Then, d is :

A beam of plane polarised light of large
cross-sectional area and uniform intensity
of 3.3 Wm^-2 falls normally on a
polariser (cross sectional area 3 $$ \times $$ 10^-4 m²) which
rotates about its axis with an angular speed
of 31.4 rad/s. The energy of light passing through
the polariser per revolution, is close to :

Two light waves having the same wavelength $$\lambda $$ in vacuum are in phase initially. Then the first wave travels a path L₁ through a medium of refractive index n₁ while the second wave travels a path of length L₂ through a medium of refractive index n₂ . After this the phase difference between the two waves is :

In a Young’s double slit experiment, light of 500 nm is used to produce an interference pattern. When the distance between the slits is 0.05 mm, the angular width (in degree) of the fringes formed on the distance screen is close to