Week 10 Homework Assignment

1. A total of 31 bright and 31dark Newton's rings (not counting the dark spot at the center) are observed when 550-nm light falls normally on a planoconvex lens resting on a flat glass surface (Fig.1). How much thicker is the center than the edge?

   

   Fig.1

2. How thick (minimum) should the air layer be between two flat glass surfaces if the glass is to appear bright when 450-nm light is incident normally? what if the glass is to appear dark?
3. Two polarizers are oriented at 40° to each other and plane-polarized light is incident on them. If only 15 percent of the light gets through both of them, what was the initial polarization direction of the incident light?
4. Suppose that a correct exposure is 1/250 s at f/11. Under the same conditions, what exposure time would be needed for a pinhole camera if the pinhole diameter is 1.0mm and the film is 7.0cm from the hole?
5. An small insect is placed 5.35cm from a +6.00-cm-focal-length lens. Calculate (a) the position of the image, and (b) the angular maagnification.