What choices of sec/div would display 2 cycles of a sine-wave signal on the screen for: (i) a 20 khz signal and (ii) a 8 mhz signal?

What is the thinnest soap film (excluding the case of zero thickness) that appears black when illuminated with light with a wavelength of 480 ? the index of refraction of the film is 1.34, and there is air on both sides of the film. express your answer in nanometers. hint 1. how to approach th

How can waves travel through ground?

Chi walked 100 meters in 5 minutes. she took another 15 minutes to walk another 400 meters to reach her house. what is her average speed?