Chapter 34, Problem 4P

### Physics for Scientists and Enginee...

10th Edition
Raymond A. Serway + 1 other
ISBN: 9781337553278

Chapter
Section

### Physics for Scientists and Enginee...

10th Edition
Raymond A. Serway + 1 other
ISBN: 9781337553278
Textbook Problem

# A dance hall is built without pillars and with a horizontal ceiling 7.20 m above the floor. A mirror is fastened flat against one section of the ceiling. Following an earthquake, the mirror is in place and unbroken. An engineer makes a quick check of whether the ceiling is sagging by directing a vertical beam of laser light up at the mirror and observing its reflection on the floor. (a) Show that if the mirror has rotated to make an angle ϕ with the horizontal, the normal to the mirror makes an angle ϕ with the vertical. (b) Show that the reflected laser light makes an angle 2ϕ with the vertical. (c) Assume the reflected laser light makes a spot on the floor 1.40 cm away from the point vertically below the laser. Find the angle ϕ.

(a)

To determine

To show: The normal to the mirror makes an angle ϕ with the vertical if the mirror has rotated to make an angle ϕ with the horizontal.

Explanation

Given info: Â The mirror has rotated an angle Ï• with the horizontal.

Figure (1)

The figure (1) shows a plane-mirror and a fixed incident ray of light reflecting from the surface at an angle Î¸ .

From, law of reflection the angle of incidence is equal to the angle of reflection.

Î¸i=Î¸r (1)

Here,

Î¸i is the angle of incidence.

Î¸r is the angle of reflection.

The mirror is rotated through an angle Ï•

(b)

To determine

To show: The reflected laser light makes an angle 2ϕ with the vertical.

(c)

To determine
The angle ϕ if the reflected laser light makes a spot on the floor 1.40cm away from the point vertically below the laser.

### Still sussing out bartleby?

Check out a sample textbook solution.

See a sample solution

#### The Solution to Your Study Problems

Bartleby provides explanations to thousands of textbook problems written by our experts, many with advanced degrees!

Get Started