Why is white light separated into a spectrum of colors when it is passed through a diffraction grating?
The diffraction angle (theta) is given by
n x (lambda) = d sine(theta)
where
lambda = wavelength
theta = diffraction angle
d = grating spacing
n = order (1,2,3 etc.)
so each wavelength is diffracted through a slightly different angle. If the incident light is white light then you will see a rainbow at each value of n.
Due to varying wavelengths, the wave speed of each constituent of the visible light spectrum will vary, and so will the angle at which the light will leave the diffraction grating. - Hope that makes some sense. (-:
When white light passes through a diffraction grating, it is separated into a spectrum of colors due to the phenomenon of diffraction. Diffraction is the bending or spreading out of light waves as they pass through an obstacle or aperture, in this case, the diffraction grating.
The diffraction grating consists of a series of closely spaced parallel lines or slits. These lines or slits act as obstacles for the light waves and cause them to diffract. According to the diffraction equation, n * lambda = d * sin(theta), where n is the order of the diffraction, lambda is the wavelength of light, d is the spacing between the lines or slits of the grating, and theta is the angle of diffraction.
White light is made up of a combination of different wavelengths, with each wavelength corresponding to a specific color. When white light passes through the diffraction grating, each wavelength is diffracted through a slightly different angle. The diffraction angle depends on the wavelength of light and the spacing between the lines or slits of the grating.
As a result, the different colors that make up white light are spread out or separated. This separation of colors forms a spectrum, commonly known as a rainbow, with different colors appearing at different angles of diffraction. Each order of diffraction (n = 1, 2, 3, etc.) corresponds to a different position of the spectrum.
Therefore, when white light is passed through a diffraction grating, the phenomenon of diffraction causes the light to separate into its component colors, resulting in a spectrum of colors being observed.
When white light passes through a diffraction grating, it interacts with the grooves on the grating surface. These grooves act as narrow slits, causing the light to diffract, or bend, as it passes through.
According to the equation you provided, the diffraction angle (theta) depends on the wavelength of light (lambda), the grating spacing (d), and the order of diffraction (n).
Since white light is a combination of different wavelengths, each wavelength is diffracted through a slightly different angle. This means that when the incident white light is passed through a diffraction grating, it will be separated into its constituent colors.
The different colors of light, with each color corresponding to a specific wavelength, are arranged in a spectrum. This is why you see a rainbow of colors when white light is diffracted through a diffraction grating, at each value of n or order of diffraction.
In summary, the diffraction grating causes the white light to diffract at different angles based on the wavelength of the light, resulting in the separation of the white light into a spectrum of colors.