A monochromatic plane wave of speed 'c' and wavelength λ is diffracted at a small aperture. The time during which a portion of the wavefront XY reaches at 'P' will be
Correct answer: B. 2λ/c
- A. 3λ/2c
- B. 2λ/c
- C. 3λ/c
- D. 4λ/c
Explanation
Explanation: The time taken for a portion of a wavefront to reach a point 'P' when a monochromatic plane wave is diffracted at a small aperture is given by the formula t=cd , where d is the distance traveled by the wavefront.For diffraction at a small aperture, the distance d is approximately equal to the size of the aperture. Therefore, d≈λ, where λ is the wavelength.Substituting d≈λ into the formula, we get t≈cλ . Therefore, the correct option is 2λ/c.
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Light is studied through reflection, refraction, dispersion, interference, diffraction and polarization, linking ray behavior with its wave nature. Questions may involve mirrors, lenses, optical instruments, refractive index and image formation, while geometrical optics deals with rays and wave optics explains effects such as interference and diffraction.
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