A monochromatic plane wave of speed c and wavelength λ is diffracted at a small aperture. The diagram illustrates successive wavefronts (vibrating in the same phase). After what time will some portion of the wavefront XY reach P ?

Question

A monochromatic plane wave of speed c and wavelength λ is diffracted at a small aperture. The diagram illustrates successive wavefronts (vibrating in the same phase). After what time will some portion of the wavefront XY reach P ?, 3 λ 2 c, 2 λ c, 3 λ c, 4 λ c

MARKS App · Accepted Answer

This distance between the 2 successive lines (wavefronts) is λ . This is for both the straight and curved lines. So, wavefront XY is separated by a distance of 3 λ from the wavefront that has reached point P. Distance that needs to be traveled = 3 λ Speed of light = c Speed = Distance/Time Time = distance/speed = 3 λ c

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