Introduction:
The instrument used to study the dispersion of light is called a spectrometer. A spectrometer is a scientific instrument that measures the intensity of different wavelengths of light. It is commonly used in physics and chemistry to analyze and study the properties of light.

Explanation:
The dispersion of light refers to the phenomenon where white light is separated into its component colors when it passes through a medium. This effect can be observed when light passes through a prism or a water droplet, creating a rainbow of colors.

A spectrometer is specifically designed to study this dispersion of light. It consists of several important components that allow for the precise measurement and analysis of different wavelengths of light.

Components of a spectrometer:
1. Collimating Lens: This lens helps in making the light rays parallel before they enter the spectrometer. It ensures that the light is focused correctly onto the other components of the spectrometer.

2. Prism or Diffraction Grating: The prism or diffraction grating is the main component that causes the dispersion of light. It separates the different wavelengths of light by bending them at different angles.

3. Slit: The slit is a narrow opening through which the light enters the spectrometer. It helps in creating a narrow and focused beam of light, which improves the accuracy of the measurements.

4. Detector: The detector is used to measure the intensity of the different wavelengths of light. It can be a photographic film, a photodiode, or a CCD (charge-coupled device) sensor.

5. Scale or Vernier: The scale or vernier is used to measure the position of the different wavelengths of light. It allows for precise measurements of the angles of dispersion.

6. Prism Table: The prism table holds the prism or diffraction grating in place. It can be adjusted to change the angle of incidence and the angle of dispersion.

Working of a spectrometer:
When white light enters the spectrometer through the slit, it passes through the collimating lens, which makes the light rays parallel. The parallel light then falls onto the prism or diffraction grating, which separates the different wavelengths of light.

The dispersed light is then focused onto the detector, where its intensity is measured. By analyzing the intensity of different wavelengths, scientists can study the properties of light and understand how it interacts with different materials.

Conclusion:
In summary, a spectrometer is the instrument used to study the dispersion of light. It allows scientists to separate and measure the different wavelengths of light, providing valuable information about the properties of light and its interactions with matter.