Question 1

Describe what happens to white light as it passes through a glass prism, explaining why this phenomenon occurs. Include a diagram to illustrate your answer.

Accepted Answer

When white light enters a glass prism, it refracts. Different colors of light within white light have different wavelengths. Shorter wavelengths (like violet) refract more than longer wavelengths (like red). This causes the white light to separate into its constituent colors, forming a spectrum. This separation is called dispersion. The diagram should show white light entering the prism, separating into different colours (red, orange, yellow, green, blue, indigo, violet), and each colour refracting at a slightly different angle.

Question 2

State the term used to describe the separation of white light into its constituent colours when it passes through a prism. Briefly explain why different colours separate.

Accepted Answer

The term is dispersion. Different colours of light have different wavelengths. When white light enters the prism, each wavelength refracts by a slightly different amount. Shorter wavelengths, like violet, bend more than longer wavelengths, like red, causing the colours to separate.

Question 3

State the seven traditional colours of the visible spectrum in order of increasing wavelength, starting with the colour that has the shortest wavelength.

Accepted Answer

1. Violet
2. Indigo
3. Blue
4. Green
5. Yellow
6. Orange
7. Red

These colours are ordered from shortest wavelength (highest frequency) to longest wavelength (lowest frequency). Remembering 'VIBGYOR' can help you recall the order.

Question 4

Describe how the frequency of light changes as you move through the visible spectrum from red to violet.

Accepted Answer

As you move from red to violet in the visible spectrum, the frequency of light increases. Red has the lowest frequency, while violet has the highest frequency of the colours in the visible spectrum.  This corresponds to a decrease in wavelength.

Question 5

Define the term 'monochromatic light'.

Accepted Answer

Monochromatic light is visible light consisting of a single frequency or wavelength. This means it appears as a single color and cannot be further dispersed into other colors by a prism or diffraction grating.  It has a single, well-defined index of refraction for a given material.

Question 6

State a common example of a source of monochromatic light.

Accepted Answer

A laser emitting a specific color (e.g., a red laser pointer emitting light at approximately 633 nm) is a common example of a source of monochromatic light. Specific types of LED which emit very narrow wavelength ranges also produce monochromatic light.

Dispersion of light

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