Wavelength of light used, λ = 6000 nm = 600 x 10-9 m Angular width of fringe, 0 = 0.1° = 0.1 x π/180 = 3.14 /1800 rad Angular width of a fringe is related to slit spacing (d) as: 0 = λ /d => d = λ/0 => d = (600 x 10-9) /(3.14/1800) = 3.44 x 10⁻4 m Therefore, the spacing between the slits isRead more
Wavelength of light used, λ = 6000 nm = 600 x 10-9 m
Angular width of fringe, 0 = 0.1° = 0.1 x π/180 = 3.14 /1800 rad
Angular width of a fringe is related to slit spacing (d) as: 0 = λ /d => d = λ/0
=> d = (600 x 10-9) /(3.14/1800) = 3.44 x 10⁻4 m
Therefore, the spacing between the slits is 3.44 x 10⁻4 m.
No Sound waves can propagate only through a medium. The two given situations are not scientifically identical because the motion of an observer relative to a medium is different in the two situations. Hence, the Doppler formulas for the two situations cannot be the same. In case of light waves, sounRead more
No
Sound waves can propagate only through a medium. The two given situations are not scientifically identical because the motion of an observer relative to a medium is different in the two situations. Hence, the Doppler formulas for the two situations cannot be the same.
In case of light waves, sound can travel in a vacuum. In a vacuum, the above two cases are identical because the speed of light is independent of the motion of the observer and the motion of the source. When light travels in a medium, the above two cases are not identical because the speed of light depends on the wavelength of the medium.
Ans (a). The speed of light in a vacuum i.e., 3 x 108 m/s (approximately) is a universal constant. It is not affected by the motion of the source, the observer, or both. Hence, the given factor does not affect the speed of light in a vacuum. Ans (b). Out of the listed factors, the speed of light inRead more
Ans (a).
The speed of light in a vacuum i.e., 3 x 108 m/s (approximately) is a universal constant. It is not affected by the motion of the source, the observer, or both. Hence, the given factor does not affect the speed of light in a vacuum.
Ans (b).
Out of the listed factors, the speed of light in a medium depends on the wavelength of light in that medium.
No; Wave theory Newton's corpuscular theory of light states that when light corpuscles strike the interface of two media from a rarer (air) to a denser (water) medium, the particles experience forces of attraction normal to the surface. Hence, the normal component of velocity increases while the comRead more
No; Wave theory
Newton’s corpuscular theory of light states that when light corpuscles strike the interface of two media from a rarer (air) to a denser (water) medium, the particles experience forces of attraction normal to the surface. Hence, the normal component of velocity increases while the component along the surface remains unchanged.
Hence, we can write the expression:
c sin i = v sin r … (i)
Where, i = Angle of incidence
r = Angle of reflection
c = Velocity of light in air
v = Velocity of light in water
We have the relation for relative refractive index of water with respect to air as: μ =v/c
Hence, it can be inferred from equation (ii) that v > c. This is not possible since this prediction is opposite to the experimental results of c > v. The wave picture of light is consistent with the experimental results.
Wavelength of Ha line emitted by hydrogen, λ = 6563 Aº = 6563 x 10⁻10 m. Star’s red-shift, (λ ' —λ ) = 15 Aº = 15 x 10-10 m Speed of light, c = 3 x 108 m/s Let the velocity of the star receding away from the Earth be v. The red shift is related with velocity as: λ ' —λ = v λ /c v = c/λ x (λ ' —λRead more
Wavelength of Ha line emitted by hydrogen, λ = 6563 Aº = 6563 x 10⁻10 m.
Star’s red-shift, (λ ‘ —λ ) = 15 Aº = 15 x 10-10 m
Speed of light, c = 3 x 108 m/s
Let the velocity of the star receding away from the Earth be v.
The red shift is related with velocity as:
λ ‘ —λ = v λ /c
v = c/λ x (λ ‘ —λ )
= (3 x 108 x 15 x 10-10 )/(6563 x 10⁻10) =6.87 x 10⁵
Therefore, the speed with which the star is receding away from the Earth is 6.87 x 10⁵ m/s.
In double-slit experiment using light of wavelength 600 nm, the angular width of a fringe formed on a distant screen is 0.1º. What is the spacing between the two slits?
Wavelength of light used, λ = 6000 nm = 600 x 10-9 m Angular width of fringe, 0 = 0.1° = 0.1 x π/180 = 3.14 /1800 rad Angular width of a fringe is related to slit spacing (d) as: 0 = λ /d => d = λ/0 => d = (600 x 10-9) /(3.14/1800) = 3.44 x 10⁻4 m Therefore, the spacing between the slits isRead more
Wavelength of light used, λ = 6000 nm = 600 x 10-9 m
Angular width of fringe, 0 = 0.1° = 0.1 x π/180 = 3.14 /1800 rad
Angular width of a fringe is related to slit spacing (d) as: 0 = λ /d => d = λ/0
=> d = (600 x 10-9) /(3.14/1800) = 3.44 x 10⁻4 m
Therefore, the spacing between the slits is 3.44 x 10⁻4 m.
See lessFor sound waves, the Doppler formula for frequency shift differs slightly between the two situations: (i) source at rest; observer moving, and (ii) source moving; observer at rest. The exact Doppler formulas for the case of light waves in vacuum are, however, strictly identical for these situations. Explain why this should be so. Would you expect the formulas to be strictly identical for the two situations in case of light travelling in a medium?
No Sound waves can propagate only through a medium. The two given situations are not scientifically identical because the motion of an observer relative to a medium is different in the two situations. Hence, the Doppler formulas for the two situations cannot be the same. In case of light waves, sounRead more
No
Sound waves can propagate only through a medium. The two given situations are not scientifically identical because the motion of an observer relative to a medium is different in the two situations. Hence, the Doppler formulas for the two situations cannot be the same.
In case of light waves, sound can travel in a vacuum. In a vacuum, the above two cases are identical because the speed of light is independent of the motion of the observer and the motion of the source. When light travels in a medium, the above two cases are not identical because the speed of light depends on the wavelength of the medium.
See lessLet 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) Wave length. (v) Intensity of the wave. On which of these factors, if any, does (a) The speed of light in vacuum, (b) The speed of light in a medium (say, glass or water), depend?
Ans (a). The speed of light in a vacuum i.e., 3 x 108 m/s (approximately) is a universal constant. It is not affected by the motion of the source, the observer, or both. Hence, the given factor does not affect the speed of light in a vacuum. Ans (b). Out of the listed factors, the speed of light inRead more
Ans (a).
The speed of light in a vacuum i.e., 3 x 108 m/s (approximately) is a universal constant. It is not affected by the motion of the source, the observer, or both. Hence, the given factor does not affect the speed of light in a vacuum.
Ans (b).
Out of the listed factors, the speed of light in a medium depends on the wavelength of light in that medium.
See lessExplain how Corpuscular theory predicts the speed of light in a medium, say, water, to be greater than the speed of light in vacuum. Is the prediction confirmed by experimental determination of the speed of light in water? If not, which alternative picture of light is consistent with experiment?
No; Wave theory Newton's corpuscular theory of light states that when light corpuscles strike the interface of two media from a rarer (air) to a denser (water) medium, the particles experience forces of attraction normal to the surface. Hence, the normal component of velocity increases while the comRead more
No; Wave theory
Newton’s corpuscular theory of light states that when light corpuscles strike the interface of two media from a rarer (air) to a denser (water) medium, the particles experience forces of attraction normal to the surface. Hence, the normal component of velocity increases while the component along the surface remains unchanged.
Hence, we can write the expression:
c sin i = v sin r … (i)
Where, i = Angle of incidence
r = Angle of reflection
c = Velocity of light in air
v = Velocity of light in water
We have the relation for relative refractive index of water with respect to air as: μ =v/c
Hence, equation (i) reduces to v/c = sini/sinr = μ … (2)
But, μ > 1
Hence, it can be inferred from equation (ii) that v > c. This is not possible since this prediction is opposite to the experimental results of c > v. The wave picture of light is consistent with the experimental results.
See lessThe 6563 Aº Ha line emitted by hydrogen in a star is found to be red shifted by 15 Aº. Estimate the speed with which the star is receding from the Earth.
Wavelength of Ha line emitted by hydrogen, λ = 6563 Aº = 6563 x 10⁻10 m. Star’s red-shift, (λ ' —λ ) = 15 Aº = 15 x 10-10 m Speed of light, c = 3 x 108 m/s Let the velocity of the star receding away from the Earth be v. The red shift is related with velocity as: λ ' —λ = v λ /c v = c/λ x (λ ' —λRead more
Wavelength of Ha line emitted by hydrogen, λ = 6563 Aº = 6563 x 10⁻10 m.
Star’s red-shift, (λ ‘ —λ ) = 15 Aº = 15 x 10-10 m
Speed of light, c = 3 x 108 m/s
Let the velocity of the star receding away from the Earth be v.
The red shift is related with velocity as:
λ ‘ —λ = v λ /c
v = c/λ x (λ ‘ —λ )
= (3 x 108 x 15 x 10-10 )/(6563 x 10⁻10) =6.87 x 10⁵
Therefore, the speed with which the star is receding away from the Earth is 6.87 x 10⁵ m/s.
See less