The band of colours obtained on a screen on passing white light through a prism is called a _____.

Explanation

**Step-by-Step Solution:**

1. **Understanding White Light**: White light is composed of multiple colors. When it passes through a prism, it can be separated into these individual colors.

2. **Using a Prism**: A prism is a transparent optical element that refracts light. When white light enters the prism, it bends at different angles depending on the wavelength (color) of the light.

3. **Formation of Colors**: As the white light exits the prism, it spreads out into a band of colors. This phenomenon occurs because different colors of light travel at different speeds in the prism material, leading to a separation of colors.

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