English Homework for Chapter 1 1.In ancient times the rectilinear propagation of light was used to measure the height of objects by comparing the length of their shadows with the length of the shadow of an object of known length. A staff 2m long when held erect casts a shadow 3.4m long, while a building’s shadow is 170m long. How tall is the building? Solu tion. According to the law of rectilinear propagation, we get, x=100 (m) So the building is 100m tall. 2.Light from a water medium with n=1.33 is incident upon a water-glass interface at an angle of 45o. The glass index is 1.50. What angle does the light make with the normal in the glass? Solu tion. According to the law of refraction, We get, So the light make 38.8o with the normal in the glass. 3. A goldfish swims 10cm from the side of a spherical bowl of water of radius 20cm. Where does the fish appear to be? Does it appear larger or smaller? Solu tion. According to the equation. and n’=1 , n=1.33, r=-20 we can get So the fish appears larger. 4.32170 x'' sinsinInIn626968.05.145sin33.1sinI8.38Irnnlnln11416.110133.15836.8)(5836.81165.02033.01033.11lnlncmlrnnlnln′=1.50 n=1.33 water 45o I′ A 4.An object is located 2cm to the left of convex end of a glass rod which has a radius of curvature of 1cm. The index of refraction of the glass is n=1.5. Find the image distance. Solu tion. Refer to the figure. According to the equation and n=1, n’=1.5, l1=-2cm, r1=1cm , we get English Homework for Chapter 2 1.An object 1cm high is 30cm in front of a thin lens with a focal length of 10cm. Where is the image? Verify your answer by graphical construction of...
