Equations dealing with the interference of light waves have a variable 'delta y'. My biggest problem is understanding what 'y' represents? Does it define the distance between two adjacent fringes? Or the distance of a fringe from the origin? this scepticism might have been the reason for my confusion in these questions. 1.) Two antennas seperated by 300m simultaneously broadcast identical signals of = wavelength. a.) A car is travelling north and is at 400m north of the midpoint line between the two signals. What is the wavelength? My solution: d=3.00m L=1000m n=2 y = 400m (from center/origin). I solved for wavelength and got an answer of 60m. the correct answer is supposedly 55.7m. Part 'b' of the question: How much further does the car have to travel to encounter the next minimum in reception? (Do not use small-angle approximation). I understand i must be solving for the dark fringes now. But the formula is confusing since 1.) i cant use small-angle approximation, and 2.) im still confused as to what 'y' represents. 2.) Light with wavelength 442nm passes through a double-slit system that has a slit seperation of 0.400mm. Determine how far the screen must be placed away from the sources to create two fringes directly across from the slits and one frindge between those. I have wavelength, distance between slits, and i could potentially find y. I must ultimately solve for L (length between screen and slits). Fistly, i have to find where the two fringes which are directly across the slits really are. I assumed that the top fringe is 'd' away from the bottom fringe. Since there is a nother frindge in betwee, the distance between frindges would be 0.4mm/2. Once again, my problem with 'y' haunts me. Should 'y' be the 0.2mm or something else? Thank you.