Diffraction of light becomes noticeable when the size of the obstacle or aperture is
Correct answer: B. comparable to the wavelength of the light
- A. much larger than the wavelength
- B. comparable to the wavelength of the light
- C. much smaller than an atom
- D. irrelevant to the wavelength
Explanation
Light bends appreciably round an obstacle only when the obstacle is of the same order of size as its wavelength, and since visible wavelengths are under a micrometre this rarely happens with everyday objects. Sound, with wavelengths of about a metre, diffracts round doorways easily, which is why you can hear round a corner but not see round it. A diffraction grating exploits slits of the right scale.
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About Optics
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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