Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
objectives
• Describe how light is reflected from a plane
surface
• Understand the law of reflection
• Be able to draw ray diagrams to show
reflection of light
keywords
• Angle of incidence
• Angle of reflection
• Incident ray
• Law of reflection
• Normal
• Perpendicular
• Plane mirror
• Protractor
• Ray diagram
• Rays
• Reflection
• Set square
Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
CONCEPTS!!!
Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
Wavelike behaviors of light
• Light exhibits behaviors that are characteristic of both waves and particles.
• Light reflects in the same manner that any wave would reflect. Light
refracts in the same manner that any wave would refract.
• A wave doesn't just stop when it reaches the end of the medium. Rather, a
wave will undergo certain behaviors when it encounters the end of the
medium. Specifically, there will be some reflection off the boundary and some
transmission into the new medium. The transmitted wave undergoes
refraction (or bending) if it approaches the boundary at an angle.
Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
Reflection of light waves
• The reflection of light waves off of a mirrored surface results in the
formation of an image.
• One characteristic of wave reflection is that the angle at which the wave
approaches a flat reflecting surface is equal to the angle at which the
wave leaves the surface. This characteristic is observed for water waves
and sound waves. It is also observed for light waves.
• Light, like any wave, follows the law of reflection when bouncing off
surfaces. The reflective behavior of light provides evidence for the wavelike
nature of light.
Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
Using the line of sight
When placed along the line of sight,
the portion of the image pencil
that extends above the mirror will
be aligned with the image that is
seen in the mirror. Then the eye
location is repositioned to the
other side of the object pencil and
the process is repeated. The
precise image location of the
object is the location where all
lines of sight intersect regardless
of where the eye is located.
Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
Using the line of sight
• As you sight at the image of an object in the mirror (whether it be a stoppered pencil or any
object), light travels along your line of sight towards your eye.
• When viewing the image of the object in a plane mirror, one of these rays of light originates
at the object location and first travels along a line towards the mirror (as represented by
the blue ray in the diagram below). This ray of light is known as the incident ray - the light
ray approaching the mirror.
• The incident ray intersects the mirror at the same location where your line of sight
intersects the mirror.
• The light ray then reflects off the mirror and travels to your eye (as represented by the red
ray in the diagram below); this ray of light is known as the reflected ray.
So the manner in which light travels to your eye as
you view the image of an object in a mirror can be
summarized as follows.
To view the image of an object in a mirror, you must
sight along a line at the image. One of the many rays
of light from the object will approach the mirror and
reflect along your line of sight to your eye.
Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
Using the line of sight
Observe in the diagram that the image is positioned directly across the mirror along a line
that runs perpendicular to the mirror. The distance from the mirror to the object (known as
the object distance) is equal to the distance from the mirror to the image (known as the
image distance). For all plane mirrors, this equality holds true:
Object distance = Image distance
Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
The following diagrams depict some ideas about how light might travel
TASK from an object location to an eye location when the image of the object
is viewed in a mirror. Comment on the incorrectness of the following
diagrams. Discuss what makes them incorrect.
A C
B
Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
TASK
This diagram depicts light moving in
curved lines. The light by which we view
objects on Earth moves in straight lines
A C
This diagram depicts light passing
B through the mirror on the way to the
mirror and on the way to the eye.
Light always reflects off the mirror;
and never passes through it.
This diagram depicts the eye looking at a location that
does not correspond to the image location. The eye
must sight along a line at the image location.
Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
Identify the source of light and then draw the path the light takes
in order for the person to see the house. You only need to draw
the path of one light beam.
In order to see an object, light is reflected off the object and intercepted by the
eye. The light travels from its source, in this case the sun, to the object. It strikes
the object and some of it is reflected off the object. The eye acts like a camera
which captures this reflected light on the retina (film) for the brain to intercept.
Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
Light Ray Reflection
Diagram
Light
Lesson 6: Reflection of light (1)
L.O. To understand reflection of light and its importance
Light Ray Reflection
Diagram
