A sonar transmitter produces 14 kHz waves in water, creating the intensity pattern shown above. The dark lines represent positions over which the intensity of the sound is constant. The intensity pattern is analogous to the effect of a single-slit interference pattern in optics. Such a device functions best when the central maximum is very narrow. Which of the following combination of changes will produce a central maximum that is the narrowest? a same frequency but halve the size of the vibrating surface b. double the frequency and halve the size of the vibrating surface c. halve the frequency and double the size of the vibrating surface d double the frequency and double the size of the vibrating surface 6 halve the frequency and halve the size of the vibrating surface S. A diffraction grating of 1000 lines/cm has red light of wavelength 700 nm pass through it. The distance between the rst and third principal bright spots on a screen 2 m away is