Dispersion of light Flashcards
Describe the dispersion of light as illustrated by the refraction of white light by a glass prism.
When white light passes through a glass prism, it refracts and splits into its component colors, forming a spectrum. Each color bends at a different angle due to varying refractive indices.
Why does dispersion occur when white light passes through a prism?
Different colors in white light have different wavelengths, and the refractive index of the prism varies with wavelength. Shorter wavelengths (like violet) bend more than longer wavelengths (like red).
State the traditional seven colors of the visible spectrum in order of frequency.
The traditional seven colors in order of increasing frequency are: red, orange, yellow, green, blue, indigo, violet.
State the traditional seven colors of the visible spectrum in order of wavelength.
The traditional seven colors in order of decreasing wavelength are: red, orange, yellow, green, blue, indigo, violet.
What is the relationship between wavelength and frequency in the visible spectrum?
As wavelength decreases, frequency increases, and vice versa. For example, red has a longer wavelength and lower frequency, while violet has a shorter wavelength and higher frequency.
Describe an experiment to demonstrate the dispersion of light using a glass prism.
- Shine a beam of white light (e.g., sunlight or from a torch) onto one face of a glass prism. 2. Observe the emerging light from another face of the prism. 3. Note the separation of colors into a visible spectrum. 4. Record the order of the colors.
Alternate-style question: How can you ensure the spectrum formed during the dispersion experiment is clear?
Use a narrow beam of white light, ensure the prism is clean and free of scratches, and place it in a dark room to clearly observe the colors.
Which color of the visible spectrum refracts the most? Why?
Violet refracts the most because it has the shortest wavelength and experiences the greatest change in speed when entering or exiting the prism.
Which color of the visible spectrum refracts the least? Why?
Red refracts the least because it has the longest wavelength and experiences the smallest change in speed when entering or exiting the prism.
Why do prisms disperse light while glass slabs do not?
In a prism, the light enters and exits at different angles, leading to dispersion. In a glass slab, the two surfaces are parallel, so the colors recombine after exiting.
Alternate-style question: How can you use a second prism to recombine the dispersed light into white light?
Place an inverted second prism in the path of the spectrum. It reverses the dispersion by bending the colors back together, forming white light.
What is the visible spectrum, and how is it related to white light?
The visible spectrum is the range of colors (red to violet) that make up white light. It becomes visible when white light is dispersed by a prism or diffraction grating.
State one application of the dispersion of light.
Dispersion is used in spectroscopy to analyze the composition of light from stars or other sources, helping to determine their chemical properties.
Alternate-style question: How can you demonstrate the visible spectrum using water instead of a prism?
Shine white light through a narrow slit onto a water droplet or a thin stream of water in sunlight. The water acts as a prism and disperses the light, forming a spectrum.
Why does violet light have a higher refractive index than red light?
Violet light has a shorter wavelength, which causes it to slow down more and bend more when passing through a medium, resulting in a higher refractive index.
