282803
Assertion: Dispersion of light occurs because velocity of light in a material depends upon its colour.
Reason: The dispersive power depends only upon the material of the prism, not upon the refracting angle of the prism.
1 If both Assertion and Reason are correct and reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
3 If Assertion is correct but Reason is incorrect
4 If both the Assertion and Reason are incorrect
Explanation:
B: Velocity of light in a material medium depends upon its colour (wavelength).
If a ray of light incident on a prism, then on emerging, different colours are deviated through different angles.
Also dispersive power \((\omega)=\left\{\frac{\mu_v-\mu_R}{\mu_y-1}\right\}\) i.e. \(\omega\) depends upon ' \(\mu\) '.
AIIMS-27.05.2018(M)
Ray Optics
282804
The focal length of thin convex lens for blue rays are \(100 \mathrm{~cm}\) and \(96.8 \mathrm{~cm}\) respectively. Then, the dispersive power of the material of the lens is
1 0.968
2 0.98
3 0.0325
4 0.325
Explanation:
C: Given,
Focal length for red rays \(\left(f_R\right)=100 \mathrm{~cm}\)
Focal length for blue rays \(\left(f_B\right)=96.8\)
We know that,
Dispersive power
\(\begin{aligned}
(\omega) & =\frac{f_R-f_B}{\sqrt{f_R f_B}} \\
\omega & =\frac{100-96.8}{\sqrt{100 \times 96.8}} \\
\omega & =0.0325
\end{aligned}\)
BITSAT-2017
Ray Optics
282805
The focal length of a lens of dispersive power 0.45 which should be placed in contact with a convex lens of focal length \(84 \mathrm{~cm}\) and dispersive power 0.21 to make the achromatic combination from the two lenses, in \(\mathrm{cm}\) is
1 45
2 90
3 180
4 -180
Explanation:
D: Given, Dispersive power of lens \(\left(\omega_1\right)=0.45\) and focal length \(=\) \(\mathrm{f}_1\)
Dispersive power of convex lens \(\left(\omega_2\right)=0.21\) and focal length \(\left(\mathrm{f}_2\right)=84 \mathrm{~cm}\)
As the lenses are placed in contact, it is achromatic condition-
\(\begin{aligned}
\frac{\omega_1}{\omega_2}=-\frac{\mathrm{f}_1}{\mathrm{f}_2} \\
\frac{0.45}{0.21}=-\frac{\mathrm{f}_1}{84} \\
\mathrm{f}_1=-\frac{45}{21} \times 84 \\
\mathrm{f}_1=-180 \mathrm{~cm}
\end{aligned}\)
AP EAMCET -2011
Ray Optics
282810
The graph which represents the relation between refractive index \(\mu\) with wavelength \(\lambda\) is
(a) (c) (b) (d) Ans: d
Exp: D: From Cauchy's Relation -
\(\begin{aligned}
\mu=A+\frac{B}{\lambda^2} \\
\mu \propto \frac{1}{\lambda^2}
\end{aligned}\)
282803
Assertion: Dispersion of light occurs because velocity of light in a material depends upon its colour.
Reason: The dispersive power depends only upon the material of the prism, not upon the refracting angle of the prism.
1 If both Assertion and Reason are correct and reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
3 If Assertion is correct but Reason is incorrect
4 If both the Assertion and Reason are incorrect
Explanation:
B: Velocity of light in a material medium depends upon its colour (wavelength).
If a ray of light incident on a prism, then on emerging, different colours are deviated through different angles.
Also dispersive power \((\omega)=\left\{\frac{\mu_v-\mu_R}{\mu_y-1}\right\}\) i.e. \(\omega\) depends upon ' \(\mu\) '.
AIIMS-27.05.2018(M)
Ray Optics
282804
The focal length of thin convex lens for blue rays are \(100 \mathrm{~cm}\) and \(96.8 \mathrm{~cm}\) respectively. Then, the dispersive power of the material of the lens is
1 0.968
2 0.98
3 0.0325
4 0.325
Explanation:
C: Given,
Focal length for red rays \(\left(f_R\right)=100 \mathrm{~cm}\)
Focal length for blue rays \(\left(f_B\right)=96.8\)
We know that,
Dispersive power
\(\begin{aligned}
(\omega) & =\frac{f_R-f_B}{\sqrt{f_R f_B}} \\
\omega & =\frac{100-96.8}{\sqrt{100 \times 96.8}} \\
\omega & =0.0325
\end{aligned}\)
BITSAT-2017
Ray Optics
282805
The focal length of a lens of dispersive power 0.45 which should be placed in contact with a convex lens of focal length \(84 \mathrm{~cm}\) and dispersive power 0.21 to make the achromatic combination from the two lenses, in \(\mathrm{cm}\) is
1 45
2 90
3 180
4 -180
Explanation:
D: Given, Dispersive power of lens \(\left(\omega_1\right)=0.45\) and focal length \(=\) \(\mathrm{f}_1\)
Dispersive power of convex lens \(\left(\omega_2\right)=0.21\) and focal length \(\left(\mathrm{f}_2\right)=84 \mathrm{~cm}\)
As the lenses are placed in contact, it is achromatic condition-
\(\begin{aligned}
\frac{\omega_1}{\omega_2}=-\frac{\mathrm{f}_1}{\mathrm{f}_2} \\
\frac{0.45}{0.21}=-\frac{\mathrm{f}_1}{84} \\
\mathrm{f}_1=-\frac{45}{21} \times 84 \\
\mathrm{f}_1=-180 \mathrm{~cm}
\end{aligned}\)
AP EAMCET -2011
Ray Optics
282810
The graph which represents the relation between refractive index \(\mu\) with wavelength \(\lambda\) is
(a) (c) (b) (d) Ans: d
Exp: D: From Cauchy's Relation -
\(\begin{aligned}
\mu=A+\frac{B}{\lambda^2} \\
\mu \propto \frac{1}{\lambda^2}
\end{aligned}\)
282803
Assertion: Dispersion of light occurs because velocity of light in a material depends upon its colour.
Reason: The dispersive power depends only upon the material of the prism, not upon the refracting angle of the prism.
1 If both Assertion and Reason are correct and reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
3 If Assertion is correct but Reason is incorrect
4 If both the Assertion and Reason are incorrect
Explanation:
B: Velocity of light in a material medium depends upon its colour (wavelength).
If a ray of light incident on a prism, then on emerging, different colours are deviated through different angles.
Also dispersive power \((\omega)=\left\{\frac{\mu_v-\mu_R}{\mu_y-1}\right\}\) i.e. \(\omega\) depends upon ' \(\mu\) '.
AIIMS-27.05.2018(M)
Ray Optics
282804
The focal length of thin convex lens for blue rays are \(100 \mathrm{~cm}\) and \(96.8 \mathrm{~cm}\) respectively. Then, the dispersive power of the material of the lens is
1 0.968
2 0.98
3 0.0325
4 0.325
Explanation:
C: Given,
Focal length for red rays \(\left(f_R\right)=100 \mathrm{~cm}\)
Focal length for blue rays \(\left(f_B\right)=96.8\)
We know that,
Dispersive power
\(\begin{aligned}
(\omega) & =\frac{f_R-f_B}{\sqrt{f_R f_B}} \\
\omega & =\frac{100-96.8}{\sqrt{100 \times 96.8}} \\
\omega & =0.0325
\end{aligned}\)
BITSAT-2017
Ray Optics
282805
The focal length of a lens of dispersive power 0.45 which should be placed in contact with a convex lens of focal length \(84 \mathrm{~cm}\) and dispersive power 0.21 to make the achromatic combination from the two lenses, in \(\mathrm{cm}\) is
1 45
2 90
3 180
4 -180
Explanation:
D: Given, Dispersive power of lens \(\left(\omega_1\right)=0.45\) and focal length \(=\) \(\mathrm{f}_1\)
Dispersive power of convex lens \(\left(\omega_2\right)=0.21\) and focal length \(\left(\mathrm{f}_2\right)=84 \mathrm{~cm}\)
As the lenses are placed in contact, it is achromatic condition-
\(\begin{aligned}
\frac{\omega_1}{\omega_2}=-\frac{\mathrm{f}_1}{\mathrm{f}_2} \\
\frac{0.45}{0.21}=-\frac{\mathrm{f}_1}{84} \\
\mathrm{f}_1=-\frac{45}{21} \times 84 \\
\mathrm{f}_1=-180 \mathrm{~cm}
\end{aligned}\)
AP EAMCET -2011
Ray Optics
282810
The graph which represents the relation between refractive index \(\mu\) with wavelength \(\lambda\) is
(a) (c) (b) (d) Ans: d
Exp: D: From Cauchy's Relation -
\(\begin{aligned}
\mu=A+\frac{B}{\lambda^2} \\
\mu \propto \frac{1}{\lambda^2}
\end{aligned}\)
282803
Assertion: Dispersion of light occurs because velocity of light in a material depends upon its colour.
Reason: The dispersive power depends only upon the material of the prism, not upon the refracting angle of the prism.
1 If both Assertion and Reason are correct and reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
3 If Assertion is correct but Reason is incorrect
4 If both the Assertion and Reason are incorrect
Explanation:
B: Velocity of light in a material medium depends upon its colour (wavelength).
If a ray of light incident on a prism, then on emerging, different colours are deviated through different angles.
Also dispersive power \((\omega)=\left\{\frac{\mu_v-\mu_R}{\mu_y-1}\right\}\) i.e. \(\omega\) depends upon ' \(\mu\) '.
AIIMS-27.05.2018(M)
Ray Optics
282804
The focal length of thin convex lens for blue rays are \(100 \mathrm{~cm}\) and \(96.8 \mathrm{~cm}\) respectively. Then, the dispersive power of the material of the lens is
1 0.968
2 0.98
3 0.0325
4 0.325
Explanation:
C: Given,
Focal length for red rays \(\left(f_R\right)=100 \mathrm{~cm}\)
Focal length for blue rays \(\left(f_B\right)=96.8\)
We know that,
Dispersive power
\(\begin{aligned}
(\omega) & =\frac{f_R-f_B}{\sqrt{f_R f_B}} \\
\omega & =\frac{100-96.8}{\sqrt{100 \times 96.8}} \\
\omega & =0.0325
\end{aligned}\)
BITSAT-2017
Ray Optics
282805
The focal length of a lens of dispersive power 0.45 which should be placed in contact with a convex lens of focal length \(84 \mathrm{~cm}\) and dispersive power 0.21 to make the achromatic combination from the two lenses, in \(\mathrm{cm}\) is
1 45
2 90
3 180
4 -180
Explanation:
D: Given, Dispersive power of lens \(\left(\omega_1\right)=0.45\) and focal length \(=\) \(\mathrm{f}_1\)
Dispersive power of convex lens \(\left(\omega_2\right)=0.21\) and focal length \(\left(\mathrm{f}_2\right)=84 \mathrm{~cm}\)
As the lenses are placed in contact, it is achromatic condition-
\(\begin{aligned}
\frac{\omega_1}{\omega_2}=-\frac{\mathrm{f}_1}{\mathrm{f}_2} \\
\frac{0.45}{0.21}=-\frac{\mathrm{f}_1}{84} \\
\mathrm{f}_1=-\frac{45}{21} \times 84 \\
\mathrm{f}_1=-180 \mathrm{~cm}
\end{aligned}\)
AP EAMCET -2011
Ray Optics
282810
The graph which represents the relation between refractive index \(\mu\) with wavelength \(\lambda\) is
(a) (c) (b) (d) Ans: d
Exp: D: From Cauchy's Relation -
\(\begin{aligned}
\mu=A+\frac{B}{\lambda^2} \\
\mu \propto \frac{1}{\lambda^2}
\end{aligned}\)
