Superposition

You will be able to

• Explain the formation of a stationary wave by the superposition of two progressive waves of the same frequency travelling in opposite directions.
• Identify nodes and antinodes and determine the wavelength as twice the distance between adjacent nodes.
• Determine the resonant frequencies of a stretched string and of an air column closed at one end or open at both ends.

You will be able to

• State the conditions for two-source interference fringes to be observed: coherent sources of the same wavelength.
• Explain bright and dark fringes in terms of a path difference of nλ and (n + ½)λ.
• Use λ = ax / D to determine the wavelength of light from a double-slit experiment.

You will be able to

• Use d sin θ = nλ, with d = 1 / N, to calculate the angles of the maxima from a diffraction grating.
• Determine the highest order that can be observed from n ≤ d / λ.
• Determine the wavelength of light from a measured angle, and explain why white light gives spectra in which red is deviated most.