PHYSICS 7C Midterm: physics7C-fa2012-mt1-Tagliaferro-soln
Document Summary
An electromagnetic wave is travelling in the +y direction. The wave is linearly polarized in the +z direction, has an amplitude of 50. 0 v m and a wavelength of 30. 0 nm. At t = 0 and y = 0, the electric eld is at a maximum and points in the +z direction. Write down the equation for the electric eld. = 6. 28 1016 rad s k = It is a cosine so that plugging in 0 gives a maximum. Write down the equation for the magnetic eld for this wave. B = 1. 67 10 7t cos(ky t) x. The b eld points in the +x direction so that e b which is proportional to z x = y points in the direction of propogation. Write down the poynting vector as well as the intensity ( the time averaged magnitude of s ) I = h|s|i = 6. 64 cos2(ky t) = 3. 32.
