1. Sources A and B emit long-range radio waves of wavelength 320 m, with the phase of the emission from A ahead of that from source B by 90°. The distance rA from A to a detector is greater than the corresponding distance rB from B by 82 m. What is the magnitude of the phase difference at the detector? 2. In a double-slit experiment the distance between slits is 5.2 mm and the slits are 0.82 m from the screen. Two interference patterns can be seen on the screen: one due to light of wavelength 450 nm, and the other due to light of wavelength 580 nm. What is the separation in meters on the screen between the m = 4 bright fringes of the two interference patterns? The first one is actually an online-test question. I have tried 3 times using the method from the textbook, but i still haven't got the right answer. Can anyone help me? THANKS!