Advertisements
Advertisements
प्रश्न
Define the term wavefront. Using Huygen’s wave theory, verify the law of reflection.
Advertisements
उत्तर
In a region where the wave is propagating, the geometrical structure formed by joining all the points which are vibrating in same (absolute) phase are said to be wavefront Reflection of plane wave :
Consider a plane wave ABC incident at an angle ‘i’ on a reflecting surface ‘AD’. If v represents the speed of the wave in medium Δt is the time taken to move from ABC to B1C1 and also from B1C1 to point ‘D’. So, at the time when a disturbance of point ‘C’ reaches to point ‘D’ disturbance of point ‘A’ must have formed a hemispherical shape of radius 2vΔt and at point ‘B1’ it must have formed a hemispherical shape of radius vΔt. Drawing a common tangent from point ‘D’ to both of the above mentioned spherical envelopes we shall have DEF as reflected wavefront. Now, in ΔACD and ΔDFA
Side AD = AD and side CD = AF = 2vΔt
And ∠ACD = ∠DFA = 90°
so by RHS rule, both the triangles are congruent. Hence each corresponding parameter must be the same. Hence ∠CAD = i (angle of incidence) Must be the same as ∠FDA = r (angle of reflection) ∠i = ∠r
APPEARS IN
संबंधित प्रश्न
Using Huygens's construction of secondary wavelets explain how a diffraction pattern is obtained on a screen due to a narrow slit on which a monochromatic beam of light is incident normally.
Using this principle draw a diagram to show how a plane wave front incident at the interface of the two media gets refracted when it propagates from a rarer to a denser medium. Hence verify Snell's law of refraction.
Light waves travel in vacuum along the X-axis. Which of the following may represent the wave fronts?
With what type of source of light are cylindrical wave fronts associated?
According to Huygen's construction, relation between old and new wavefront is ______.
Answer the following question briefly and to the point:
What is the phase difference between any two points lying on the same wavefront?
Figure shows a standard two slit arrangement with slits S1, S2, P1, P2 are the two minima points on either side of P (Figure). At P2 on the screen, there is a hole and behind P2 is a second 2-slit arrangement with slits S3, S4 and a second screen behind them.
Two light beams of intensities in the ratio of 9 : 4 are allowed to interfere. The ratio of the intensity of maxima and minima ______.
Using Huygen’s wave theory of light, show that the angle of incidence is equal to the angle of reflection. Draw a neat and labelled diagram.
Represent diagrammatically how the incident planar wavefronts of wavelength λ pass through an aperture of size d, when d is approximately equal to λ.
