The wavelength of sound in air can be found by making use of stationary waves. In one investigation, a loudspeaker emits a sound wave of fixed frequency, and a metal plate about $1\,\text{m}$ away reflects it straight back along the same route. A microphone linked to a cathode-ray oscilloscope (CRO) is then shifted between the loudspeaker and the plate to locate positions of maximum sound intensity ('loud' spots) and minimum sound intensity ('quiet' spots). The sound wavelength is calculated using the smallest possible number of measured quantities. Which row gives the quantities that are required?
Physics 9702 · AS & A Level · Stationary waves