Explain why constructive interference occurs along lines A, , A, and A , . Calculate the num ber of nodal lines and find the angles they make with the line A . C How many nodal lines would there be if the sources were moved to ten wavelengths apart? How many antinodal lines would there t then be ? d Calculate the angle e It is not possible to see the two sets of circular waves separately as shown in the diagram . Sketch the actual appearance of the waves a at the instant shown . 10 Two sources of identical sound waves, S, and S, , are separated by a small distance as shown in the diagram below X D S1 P Y A detector , D , is set up so that it moves between X and Y . A graph of the intensity of the sound measured by the detector is shown below intensity of sound X P Y Carefully explain why such a pattern is observed. What is the effect on the intensity pattern : if the sources are moved further apart? ii if the wavelength emitted by the sources is increased? Describe how a minimum r a maxim um intensity of sound can be produced at P without moving the sources or altering the frequency