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
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
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
A goldfish swims 10cm from the side of