Dispersion and Spectra Physics - Dispersion and Spectra

Which of the following quantities increase when wavelength is increased? Consider only the magnitudes.

1. The power of a converging lens.
2. The focal length of a converging lens.
3. The power of a diverging lens.
4. The focal length of a diverging lens.

Which of the following quantities related to a lens depend on the wavelength or wavelengths of the incident light?

1. Power.
2. Focal length.
3. Chromatic aberration.
4. Radii of curvature.

In producing a pure spectrum, the incident light is passed through a narrow slit placed in the focal plane of an achromatic lens because a narrow slit:

1. Produces less diffraction.
2. Increases intensity.
3. Allows only one colour at a time.
4. Allows a more parallel beam when it passes through the lens.

A narrow beam of white light goes through a slab having parallel faces.

1. The light never splits in different colours.
2. The emergent beam is white.
3. The light inside the slab is split into different colours.
4. The light inside the slab is white.

Consider the following two statements:

1. Line spectra contain information about atoms.
2. Band spectra contain information about molecules.

1. Both A and B are wrong
2. A is correct but B is wrong.
3. B is correct but A is wrong
4. Both A and B are correct.

The refractive index of a material changes by 0.014 as the colour of the light changes from red to violet. A rectangular slab of height 2.00cm made of this material is placed on a newspaper. When viewed normally in yellow light, the letters appear 1.32cm below the top surface of the slab. Calculate the dispersive power of the material.

The minimum deviations suffered by red, yellow and violet beams passing through an equilateral transparent prism are 38.4°, 38.7° and 39.2° respectively. Calculate the dispersive power of the medium.

Suggest a method to produce a rainbow in your house.

A thin prism is made of a material having refractive indices 1.61 and 1.65 for red and violet light. The dispersive power of the material is 0.07. It is found that a beam of yellow light passing through the prism suffers a minimum deviation of 4.0° in favourable conditions. Calculate the angle of the prism.

Does focal length of a lens depend on the colour of the light used? Does focal length of a mirror depend on the colour?

Two prisms of identical geometrical shape are combined with their refracting angles oppositely directed. The materials of the prisms have refractive indices 1.52 and 1.62 for violet light. A violet ray is deviated by 1.0° when passes symmetrically through this combination. What is the angle of the prisms?

A certain material has refractive indices 1.56, 1.60 and 1.68 for red, yellow and violet light respectively.

1. Calculate the dispersive power.
2. Find the angular dispersion produced by a thin prism of angle 6° made of this material.

The refractive index of a material M₁ changes by 0.014 and that of another material M₂ changes by 0.024 as the colour of the light is changed from red to violet. Two thin prisms one made of M₁(A = 5.3°) and other made of M₂(A = 3.7°) are combined with their refracting angles oppositely directed.

1. Find the angular dispersion produced by the combination.
2. The prisms are now combined with their refracting angles similarly directed. Find the angular dispersion produced by the combination.