Mr' Perez

1
Mr. Perez

• Grade 6 Science
• Mirrors, Reflections, and Angles

2
Finding Angles with Mirrors

• A hinged mirror is made of two mirrors that are
  connected by a hinge that allows the mirrors to
  open and close like a door
• When you place an object between two hinged
  mirrors, light from the object bounces back and
  forth between the mirrors before it reaches your
  eyes
• An image is formed each time the light bounces
  off of the mirrors
• The angle between the two hinged mirrors has a
  special relationship with the number of images
  you see
• The number of images can be calculated by using a
  formula

3
How do you find the angle?

• To find the angle of the hinged mirrors
• Place one end object at the vertex (which is
  where both mirrors meet) of the two mirrors and
  align the rest of the object with the optical
  axis
• Count the number of images that you see in both
  mirrors. Be careful, one reflected image might
  be where the two mirrors come together
• Add one to this number (to include the actual
  object)
• Divide that number into 360?
• The quotient (your answer) will be the angle of
  the mirrors

4
Calculating the Angle of the Mirrors

• How many reflected images do you see?
• One reflected image
• Add one to this number (to include the actual
  pencil)
• 1 1 2 images
• Calculate the angle by using the formula

• Angle of Mirrors 360? ? Number of Images
• Angle of Mirrors 360? ? 2
• Angle of Mirrors 180?

5
Calculating the Angle of the Mirrors

• How many reflected images do you see?
• Nine reflected images
• Add one to this number (to include the actual
  pencil) 9 1 10 images
• Calculate the angle by using the formula

• Angle of Mirrors 360? ? of Images
• Angle of Mirrors 360? ? 10
• Angle of Mirrors 36?

6
Calculating the Number of Reflected Images

• To find the number of reflected images, use the
  following formula
• of Reflected Images (360? ? Angle of Mirrors)
  - 1
• Why do you need to subtract one?
• Because the actual object is NOT a reflected
  image
• Ex How many reflected images will you see in
  two hinged mirrors that have a 60? angle?

• of Reflected Images (360? ? Angle of Mirrors)
  - 1
• of Reflected Images (360? ? 60?) - 1
• of Reflected Images 6 - 1
• of Reflected Images 5

7
Calculating the Number of Reflected Images

• Ex How many reflected images will you see in
  two hinged mirrors that have a 20? angle? Write
  the formula and use your notes.

• of Reflected Images (360? ? Angle of Mirrors)
  - 1

8
The answer is

• Ex How many reflected images will you see in
  two hinged mirrors that have a 20? angle? Write
  the formula and use your notes.

• of Reflected Images (360? ? Angle of Mirrors)
  - 1
• of Reflected Images (360? ? 20?) - 1
• of Reflected Images 18 - 1
• of Reflected Images 17