1. Interference in thin films: A biprism can be used to observe the interference fringes. By placing a thin film of transparent material, such as a soap film or a glass plate, between the two prisms, the light waves from the two sources will interfere with each other, producing a series of bright and dark bands. The thickness of the film can be determined by measuring the spacing of the interference fringes.

2. Determination of the wavelength of light: The wavelength of light can be determined by using a biprism and a spectrometer. By placing a biprism in front of the collimator of the spectrometer, the light from the source will be split into two beams, which will then be diffracted by the grating of the spectrometer. The resulting interference pattern can be used to measure the wavelength of the light.

3. Measurement of refractive index: The refractive index of a liquid or a solid can be determined by using a biprism and a refractometer. By placing the liquid or solid between the two prisms, the light waves from the two sources will be refracted, causing the interference fringes to shift. The amount of shift can be used to calculate the refractive index of the material.

4. Study of dispersion: Dispersion is the phenomenon of the variation of the refractive index of a material with the wavelength of light. A biprism can be used to study the dispersion of a material by placing a prism made of the material between the two prisms. The resulting interference pattern will show the dispersion of the material, which can be used to calculate the Cauchy coefficients of the material.

5. Holography: Biprisms are used in holography to create interference patterns that are used to record holograms. Holography is a technique that allows the recording and reconstruction of three-dimensional images of objects.