Image Characteristics

Worksheet Answers

Location  The object is the same distance to the mirror as the image is to the mirror.

Attitude/Orientation

The image is upright.

Size The image is the same size as the object.

Type The image is reversed compared to the object.

State the four LAST characteristics of an image in a plane mirror.

Place where light rays actually cross or appear to cross.

real: light rays actually cross in front of mirrorvirtual: light rays appear to cross behind mirror

Angle of Incidence (i) angle between the incident ray and the normal

Angle of Reflection (r) angle between the reflected ray and the normal

Incident Ray incoming light ray

Normaldashed line drawn perpendicular to the mirror at the point of reflection

Reflected Ray light ray reflected from the mirror

4. Define the following optical terms.

2. What does virtual image mean?

3. Relate each letter in the diagram to one of the following optical terms

A virtual image is the image of an object in a mirror.

angle of incidence (i) normal angle of reflection (r) incident rayreflected ray

b)

a)c)

d)

e)

f)

g)

h)

c)d)e)b)f)

5. State the Laws of Reflection from a plane mirror.

- The angle of incidence is equal to the angle of reflection.

- The incident ray, the normal, and the reflected ray all lie on the same plane.

6. Does a candle have to be in front of a mirror in order to form an image? Try It!

Both candles can form images. The “mirror” must be extended to find the location of the image for candle #2.

It is there, but how must you look?

Measure the distance from the top of the object to the mirror (dO).

Copy this distance (dOtop) to the other side of the mirror. It becomes (dItop).

Repeat this process for the bottom of the object.

These two points give the location of the top and bottom of the image. For any point dO = dI.

Rays of light must be entering the eye as if they had come straight from the image.

That is the way the eye sees things.

The line is dotted behind the mirror because light rays cannot go through an opaque mirror.

They travel in this direction but could not have come from the image’s location.

The light rays that appear to come from the top of the image really came from the top of the object and reflect off the mirror into the eye.

The light rays that appear to come from the bottom of the image really came from the bottom of the object and reflect off the mirror into the eye.

Your Turn

Complete question #8

A) should look like this.

B) should look like this.

C) should look like this.

D) should look like this.

9. Which Eye-Brains can see the image #1?

Image #1

10.Which Eye-Brains can see image #2 in the mirror?

Image #2

11. Show where the Images are located …………

12. Which Eye-Brain can see

ii) Image of candle #2

13. What determines whether an Eye-Brain observer can see an image or not?

There must be straight line connecting eye to the image.

A, B, C, D?A, B, C, D?

14.Use the laws of reflection to show how the eye-brain sees the top and bottom of a candle in a periscope.

Roughly parallel rays from the top and bottom of the candle move towards the top mirror.

Angle of Incidence = Angle of Reflection (i = r )

the rays move towards the bottom mirror

Angle of Incidence = Angle of Reflection (i = r ) and the rays move towards the Eye-Brain mirror.

The candle’s image appears erect or upright.

15.Use the laws of reflection to show how the eye-brain sees the top and bottom of a candle if the top mirror is be rotated to face backwards?

Roughly parallel rays from the top and bottom of the candle move towards the top mirror.

Angle of Incidence = Angle of Reflection (i = r )

rays move towards the bottom mirror

Angle of Incidence = Angle of Reflection (i = r ) and the rays move towards the Eye-Brain.

The candle’s image appears inverted.

16. How do Bicycle Reflectors Work?

Why not just use a mirror to reflect light back into the Eye-Brain?

Because slight changes in the mirror’s orientation would cause the reflected light to miss the Eye-Brain.

If two mirrors are arranged at 90º, ......

If two mirrors are arranged at 90º, slight changes in the mirrors’ orientation do not affect the general direction of the reflected light.

The incident ray hitting a reflector is sent back in the same direction