Differentiate between a glass slab and a glass prism. What happens when a narrow beam of (i) a monochromatic light, and (ii) white light passes through (a) glass slab and (b) glass prism?

A glass slab and a glass prism are both transparent optical elements made of glass, but they have distinct shapes and properties that affect how light interacts with them.

Glass Slab:
A glass slab is a flat, rectangular piece of glass with parallel faces. When light passes through a glass slab, it undergoes refraction at each surface due to the change in the refractive index between air and glass. The refraction causes the light to change its direction, but there is no dispersion (separation of different colors) since the glass slab has parallel sides.

Glass Prism:
A glass prism is a three-dimensional transparent object with two triangular faces and a rectangular cross-section. The angles of the triangular faces are not equal, which gives the prism its ability to disperse light into its component colors (i.e., create a rainbow effect).

(i) When a narrow beam of monochromatic light (light of a single wavelength or color) passes through a glass slab:
The light beam will undergo refraction at each surface of the glass slab, causing it to change direction. However, since it is monochromatic light (single wavelength), there will be no dispersion, and the output beam will remain a narrow beam of the same color, but with a change in direction.

(ii) When a narrow beam of white light (which is a combination of all colors in the visible spectrum) passes through a glass slab:
The white light consists of various colors with different wavelengths. As the light passes through the glass slab, each color will experience refraction based on its specific wavelength. However, since the sides of the glass slab are parallel, all colors will experience the same amount of refraction, resulting in the white light remaining together and not dispersing. The output beam will still be a narrow beam of white light, but with a change in direction.

(a) When a narrow beam of white light passes through a glass prism:
As the white light enters the prism, it undergoes refraction at each boundary due to the change in refractive index at the surfaces. However, the angles of the prism's triangular faces cause different colors to experience different amounts of refraction, leading to the phenomenon of dispersion. The light is split into its component colors, creating a spectrum of colors (rainbow) on the other side of the prism.

(b) When a narrow beam of monochromatic light passes through a glass prism:
A monochromatic light beam, consisting of a single color, will also experience refraction as it enters the prism. However, since there are no other colors to disperse, the output beam will remain a narrow beam of the same color but with a change in direction due to refraction.

In summary, a glass slab does not disperse light and only changes the direction of the light beam, while a glass prism disperses white light into its component colors due to varying degrees of refraction for each color. For monochromatic light, both the glass slab and glass prism cause a change in direction without dispersion.