╞╡§¥ Physics SPM 2013 Chapter 5: Light and VisionHoo Sze Yen www.physicsrox.comPage 1 of 8CHAPTER 5: LIGHT AND VISION These notes have been compiled in a way to make it easier for revision. The topics are not in order as per the syllabus. 5.1Mirrors and Lenses 5.1.1Image Characteristics Image characteristics are described using the following three categories: Size Same Image is exa ctly the same size as the o bject Magnified Image appe ars bigger th an the obje ct Diminished Image appe ars smaller th an the ob ject Direction Upright Image appe ars to be in th e same dire ction as the object Inverted Image appe ars upside d own comp ared to obje ct Type Real Real images a re images y ou can c apture on a s creen. Mirrors: Ima ges are formed on the sa m e side of the mirror as the object Lenses: Imag es are formed on the opposite side of the lens from the object Virtual Virtual images are images you can see but cannot capture on a screen. Mirrors: Ima ges are formed on the opposite side of the mirror from the object Lenses: Imag es are formed on the same side of the lens as the object 5.1.2Plane mirrors Law of l ight reflection: •The reflected angle is always the sameas the incident angle. •The incident ray, reflected ray, and normal line ar e in the same plane. Character istics of an image formed by a plane mirror: Size Same Direction Upright, laterally inverted Type Virtual Distance Distance of an image from the plane mirror is the same as the dist ance of the object from the mirror normalIncident rayReflected ray
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Physics Final Revision - Light and Vision 2013.pdf
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7/27/2019 Physics Final Revision - Light and Vision 2013.pdf
These notes have been compiled in a way to make it easier for revision. The
topics are not in order as per the syllabus.
5.1 Mirrors and Lenses
5.1.1 Image Characteristics
Image characteristics are described using the following three categories:
Size Same Image is exactly the same size as the object
Magnified Image appears bigger than the object
Diminished Image appears smaller than the object
Direction Upright Image appears to be in the same direction as the object
Inverted Image appears upside down compared to object
Type Real Real images are images you can capture on a screen. Mirrors: Images are formed on the same side of the mirror as the object Lenses: Images are formed on the opposite side of the lens from the object
Virtual Virtual images are images you can see but cannot capture on a screen. Mirrors: Images are formed on the opposite side of the mirror from the object Lenses: Images are formed on the same side of the lens as the object
5.1.2 Plane mirrors
Law of light reflection:• The reflected angle is always the same as the incident angle.
• The incident ray, reflected ray, and normal line are in the same plane.
Characteristics of an image formed by a plane mirror:
Size Same
Direction Upright, laterally inverted
Type Virtual
Distance Distance of an image from the plane mirror is the same as the distance of
the object from the mirror
normal Incident ray Reflected ray
7/27/2019 Physics Final Revision - Light and Vision 2013.pdf
Determining the Position and Characteristics of an Image with a Ray Diagram
Concave mirror
A ray parallel to the principal axis is reflected to pass through F
A ray through F is reflected parallel to the principal axis
A ray through C is reflected back along its own path
Convex mirror
A ray parallel to the principal axis is reflected as if
it came from F
A ray towards F is reflected parallel to the principal axis
A ray towards C is reflected back along its own path
Convex lens
A ray parallel to the principal axis is refracted to pass through F
A ray through F is refracted parallel to the principal axis
A ray through C travelsstraight along its own path
Concave lens
A ray parallel to the principal axis is refracted as if it came from F
A ray towards F is refracted parallel to the principal axis
A ray towards C travelsstraight along its own path
To determine the position and characteristics of an image using a ray diagram:
1. Draw two rays emanating from the top of the object to the mirror or lens, and using the guide in the tableabove, draw their reflected/refracted paths.
2. The image is produced at the intersection of the two reflected/refracted rays.
7/27/2019 Physics Final Revision - Light and Vision 2013.pdf
Light refraction is a phenomenon where the direction of light is changed when it crosses the
boundary between two materials of different optical densities. It occurs as a result of achange in the speed of light as it passes from one medium to another.
When a light ray travels from medium A
to medium B which is optically denser
than A
When a light ray travels from medium C
to medium D which is optically denser
than C
The ray of light will refract towards
normal; r < i
The ray of light will refract away from
normal; r > i
When a light ray crosses the boundary between two different mediums at a right
angle
i = 0°, r = 0°
5.2.1 Snell’s Law
Snell’s Law states that the ratio of sin i to sin r is a constant.
r
i
sin
sin= constant
7/27/2019 Physics Final Revision - Light and Vision 2013.pdf