Questions
The angles of minimum deviations are 53$^{\circ}$ and 51$^{\circ}$ for blue and red colors respectively produced in an equilateral glass prism. The dispersive power is :
- $\dfrac{2}{51}$
- $\dfrac{1}{26}$
- $\dfrac{1}{52}$
- $\dfrac{1}{51}$
If the refractive indices of crown glass for red, yellow and violet colours are respectively ${ \mu } _{ r },{ \mu } _{ y },{ \mu } _{ v }$, then the dispersive power of this glass would be
- $\cfrac { { \mu } _{ v }-{ \mu } _{ r } }{ { \mu } _{ y }-1 } $
- $\cfrac { { \mu } _{ v }-{ \mu } _{ y } }{ { \mu } _{ r }-1 } $
- $\cfrac { { \mu } _{ v }-{ \mu } _{ y } }{ { \mu } _{ y }-{ \mu } _{ r } } $
- $\cfrac { { \mu } _{ v }-{ \mu } _{ r } }{ { \mu } _{ y } } -1$
The dispersion of a medium for wavelength $\lambda$ is D. Then the dispersion for the wavelength $2\lambda$ will be:
- $(D/8)$
- $(D/4)$
- $(D/2)$
- D
In a prism, the refractive indices of different colours are
$\mu _{V} =$ 1.6;
$\mu _{R} =$ 1.52;
$\mu _{Y} =$ 1.56.
The dispersive power of the prism is :
- $\dfrac{1}{56}$
- $\dfrac{1}{8}$
- $\dfrac{1}{7}$
- Infinite
A flint glass prism is of refracting angle 5$^{\circ}$. Its refractive index for C line is 1.790 and for F line is 1.805. The angular dispersion of C and F lines is:
- 0.075$^{\circ}$
- 0.085$^{\circ}$
- 0.095$^{\circ}$
- 0.065$^{\circ}$
Dispersive power of the material of a prism is 0.0221. If the deviation produced by it for yellow colour is 38$^{\circ}$, then the angular dispersion between red and violet colours is :
- 0.65$^{\circ}$
- 0.84$^{\circ}$
- 0.48$^{\circ}$
- 1.26$^{\circ}$
The dispersive power of a medium is
- The greatest for red light
- the least for red light
- the least for yellow light
- the ate for at colours
The difference between angle of minimum deviation for violet and red rays in the spectrum of white light from a prism is $2^0$. If the angle of minimum deviation of the mean ray is $48^0$, the dispersive power of the material of the prism is
- $24^0$
- $48^0$
- 0.0416
- 0.0832
The focal length of a thin convex lens for red and blue rays are $100\ cm$ and $96.8\ cm$ respectively. The dispersive power of the material of the lens is
- 0.0325
- 0.825
- 0.968
- 0.98
If a glass prism is dipped in water, its dispersive power
- increases
- decreases
- does not change
- may increase or decrease depending on whether the angle of the prism is less than or greater than $60^o$
Two thin prisms of flint glass, with refracting angles of $6^o$ and $8^o$ respectively, possess disperse powers in the ratio
- 4 : 3
- 3 : 4
- 1 : 1
- 9 : 16
Refractive index of glass for red and violet colours are $1.64$ and $1.66$ respectively. Dispersive power of the prism is :
- $0.3$
- $3.3$
- $1.33$
- $.03$
The refractive index of flint glass for blue line is 1.6333 and red line is 1.6161, then dispersive power of the glass is :
- 0.0276
- 0.276
- 2.76
- 0.106
Using the following data,choose the correct option:
C D F
Crown 1.5145 1.5170 1.5230
FLINT 1.6444 1.6520 1.6637
- The dispersive power for crown glass is 0.1644
- The dispersive power for flint glass is 0.029601
- The dispersive power for crown is 0.01644
- The dispersive power for flint glass is 1.29601
If D is the deviation of a normally falling light beam on a thin prism of angle a and $\delta$ is the dispersive power of the same prism then
- D is independent of A
- D is independent of refractive Index
- $\delta$ is independent of refractive index
- $\delta$ is independent of A
If a glass prism is dipped in water, its dispersive power
- increases
- decreases
- does not change
- may increase or decreases depending on whether the angle of the prism is less than or greater than $ { 60 }^{ \circ }$
A thin prism deviates blue and red rays through 10$^{\circ}$ and 6$^{\circ}$respectively. Another prism deviates same colours through 8$^{\circ}$ and 4.5$^{\circ}$ respectively.The ratio of dispersive powers of the prisms is :
- 5:4
- 4:5
- 25:28
- 5:28
A prism of a certain angle deviates the red and blue rays by $8$ and $12$ respectively. Another prism of the same angle deviates the red and blue rays by $10$ and $14$ respectively. The prisms are small angled and made of different materials. The dispersive powers of the materials of the prisms are in the ratio
- $11 : 9$
- $6 : 5$
- $9 : 11$
- $5 : 6$
When a beam of light is used to determine the position of an object, the maximum accuracy is achieved if the light is.
- Polarised
- Of longer wavelength largest
- Of shorter wavelength
- Of high intensity
Calculate the dispersive power for glass from the given data $\mu _v=1.523$, and $\mu _r=1.5145$.
- 0.0012
- 0.2333
- 0.1639
- 0.9
If the refractive indices of a prism for red, yellow and violet colours be 1.61, 1.63 and 1.65 respectively, then the dispersive power of the prism will be:
- $\dfrac { 1.65-1.62 }{ 1.61-1 }$
- $\dfrac { 1.62-1.61 }{ 1.65-1 }$
- $\dfrac { 1.65-1.61 }{ 1.63-1 }$
- $\dfrac { 1.65-1.63 }{ 1.61-1 }$