The following are the causes of flickering:

Concept: Dispersion is defined as the spread of white light across its entire wavelength spectrum. Dispersion occurs when the propagation of light is affected by wavelength.

Because the refractive index varies with colour, when white light passes through a glass prism, its constituent colours (red, orange, yellow, green, blue, indigo, and violet) travel at different speeds. Light is dispersed as a result of this.