Q. A steel cable with total length 20m and mass 100kg is connected to two poles. The tension in the cable is 2,000 N, and the wind makes the cable vibrate with a frequency of 2 Hz. Calculate the wavelength of the resulting wave on the cable.

Q. You illuminate two slits 0.50 mm apart with light of wavelength 555 nm and observe interference fringes on a screen 6.0 m away. What is the spacing between the fringes on the screen? 2. If a thin soap film (n = 1.36) reflects predominately red light (about 680 nm), then what is the minimum thickness of the soap film? A) 1.25 ? 107 m B) 6.80 ? 107 m C) 2.50 ? 107 m D) 5.00 ? 107 m E) None of these is correct. 3. You apply a material with n = 1.25 to a lens (ng = 1.5) to make a nonreflective coating due to destructive interference at a wavelength (in a vacuum) of 555 nm. What is the minimum thickness of the coating that you need?