The wave front formed at a very large distance from a light source is
Correct answer: C. Plane wave front
- A. Cylindrical wave front
- B. Spherical wave front
- C. Plane wave front
- D. Elliptical wave front
Explanation
When light emanates from a point source, it initially forms spherical wave fronts. However, as these wave fronts travel further away from the source, the curvature decreases and they begin to resemble plane wave fronts. This is due to the wave fronts being so far from the source that the radius of curvature becomes very large, making them appear flat or planar. Therefore, at a very large distance from a light source, the wave front is best described as plane (Option C).Option A, 'Cylindrical wave front,' is incorrect because cylindrical wave fronts are associated with line sources rather than point sources. Option B, 'Spherical wave front,' describes the initial form of the wave front but not its form at large distances. Option D, 'Elliptical wave front,' is incorrect because elliptical wave fronts are not typically formed by simple light sources under these conditions.
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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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