Author Question: Ninety percent of light incident on a certain piece of glass passes through it. How much light ... (Read 55 times)

AEWBW · **on:** Jul 29, 2018

Ninety percent of light incident on a certain piece of glass passes through it. How much light passes through two pieces of this glass?

A) 80
B) 81
C) 85
D) 89
E) 90

Question 2

When a mirror with a fixed beam on it is rotated through a certain angle, the reflected beam is rotated through an angle that is

A) equal to the angle of rotation.
B) twice as large.
C) four times as large.
D) none of these