Advertisements
Advertisements
प्रश्न
The wavefronts of light coming from a distant source of unknown shape are nearly _________ .
विकल्प
plane
elliptical
cylindrical
spherical
Advertisements
उत्तर
plane
Wave travelling from a distant source always has plane wavefront.
APPEARS IN
संबंधित प्रश्न
The refractive index of glass is 1.5. What is the speed of light in glass? (Speed of light in vacuum is 3.0 × 108 m s−1)
Is the speed of light in glass independent of the colour of light? If not, which of the two colours red and violet travels slower in a glass prism?
Let us list some of the factors, which could possibly influence the speed of wave propagation:
(i) Nature of the source
(ii) Direction of propagation
(iii) Motion of the source and/or observer
(iv) Wavelength
(v) Intensity of the wave
On which of these factors, if any, does the speed of light in vacuum?
A plane wavefront propagating in a medium of refractive index 'μ1' is incident on a plane surface making the angle of incidence 'i' as shown in the figure. It enters into a medium of refractive index 'μ2' (μ2 > μ1). Use Huygens' construction of secondary wavelets to trace the propagation of the refracted wavefront. Hence verify Snell's law of refraction.
The wavefronts of a light wave travelling in vacuum are given by x + y + z = c. The angle made by the direction of propagation of light with the X-axis is _________ .
Light waves travel from optically rarer medium to optically denser medium. Its velocity decreases bec;ause of change in ______.
The optical properties of a medium are governed by the relative permittivity (εr) and relative permeability (µr). The refractive index is defined as `sqrt(µ_r ε_r) = n`. For ordinary material εr > 0 and µr > 0 and the positive sign is taken for the square root. In 1964, a Russian scientist V. Veselago postulated the existence of material with εr < 0 and µr < 0. Since then such ‘metamaterials’ have been produced in the laboratories and their optical properties studied. For such materials `n = - sqrt(µ_r ε_r)`. As light enters a medium of such refractive index the phases travel away from the direction of propagation.
- According to the description above show that if rays of light enter such a medium from air (refractive index = 1) at an angle θ in 2nd quadrant, them the refracted beam is in the 3rd quadrant.
- Prove that Snell’s law holds for such a medium.
A glass slab of thickness 4 cm contains the same number of waves as 5 cm of water. When both are traversed by the same monochromatic light. If the refractive index of water is `(4/3)`. What is that of glass?
White light is an incident at 20° on a material of silicate flint glass slab as shown. `μ_"violet"` = 1.66 and µr = 1.6. For what value of d will the separation be 1 mm in red and violet rays?
A light ray in a medium (RI = 5/3) enters another medium at an angle of 30°. The angle in the other medium is sin-1 (5/6). The incident angle must be increased such that the ray is completely reflected at minimum degrees is ______.
In the refraction construction, which medium is assumed to be denser?
What is the direction of the refracted ray relative to the refracted wavefront?
Which refractive index corresponds to medium 1?
When a light wave travels from one medium to another, which property remains the same?
Which expression gives the wavelength of light in medium 1?
How does the speed of light in a denser medium compare with its speed in a rarer medium?
Which picture of light was needed to address why its speed differs between media?
How does the wave picture's conclusion about the speed of light in a denser medium compare with that deduced from the particle picture?
