How do you calculate the angle of diffraction?

The angle of diffraction can be calculated using Bragg's Law, which relates the wavelength of light, the angle of incidence, and the distance between diffracting planes.

Bragg's Law, named after the British scientists William Henry Bragg and his son William Lawrence Bragg, is a fundamental equation in the study of diffraction and crystallography. It states that nλ = 2d sin θ, where n is the order of diffraction, λ is the wavelength of the incident wave, d is the distance between diffracting planes (often atomic layers in a crystal), and θ is the angle of incidence, which is also the angle of diffraction.

To calculate the angle of diffraction, you would rearrange the equation to solve for θ: θ = arcsin(nλ / 2d). This means that you need to know the order of diffraction, the wavelength of the incident wave, and the distance between the diffracting planes.

The order of diffraction, n, is a positive integer that represents the number of wavelengths that fit into the path difference. In simpler terms, it's the number of 'bounces' the wave makes off the diffracting planes. For most basic diffraction problems, you can assume n=1.

The wavelength of the incident wave, λ, is often given in the problem or can be determined from the type of wave. For example, visible light has a wavelength in the range of 400-700 nanometres.

The distance between diffracting planes, d, is typically given in the problem or can be determined from the properties of the material. For example, in a crystal lattice, d would be the distance between atomic layers.

Once you have these values, you can plug them into the rearranged Bragg's Law equation to find the angle of diffraction. Remember to use the arcsin function on your calculator, and ensure it's set to give the answer in degrees (not radians) if the question asks for the angle in degrees.

IB Physics Tutor Summary: To calculate the angle of diffraction, you use Bragg's Law, which needs the order of diffraction (n), the wavelength (λ), and the distance between planes (d). Simply rearrange Bragg's Law to solve for the angle (θ = arcsin(nλ / 2d)). It's key to know these three values to find the angle, usually given in degrees. Ensure your calculator is set correctly!