Physics Light, Prisms & Lenses - Properties, Functions, Refraction and Key Equations
Light, Prisms & Lenses - Properties, Functions, Refraction and Key Equations
Table of Contents
1. The properties of light
1.1 Key Terminology for Light
1.2 Structure and Nature of Light (wave-particle duality, transverse wave)
1.3 Interaction with Matter
Reflection (specular and diffuse)
Refraction and its effects
Total Internal Reflection
1.4 Snell’s Law (definition, equations, applications)
2. Prisms
2.1 Key Terminology for Prisms
2.2 Definition and Structure of a Prism
3. Lenses
3.1 Key Terminology for Lenses
3.2 Lens Types and Structure
3.3 Lens Equations
Focal length, object & image distance
Magnification formulas
4. Additional questions for light and prisms
1
,Physics Light, Prisms & Lenses - Properties, Functions, Refraction and Key Equations
1. The properties of light
1. Key words for light:
1. Transparent= An object that light can pass through.
2. Ray diagram= A diagram showing the path of the light.
3. Distort= When what you see gets twisted and messed up, like fairground mirrors.
4. Refractive Index=A measure of the bending of a ray of light when passing from one medium into
another.
5. Vacuum= A space with nothing in it.
6. Medium= The material light is travelling through.
7. Critical angle= The highest angle at which refraction is observed.
8. Optically dense= Refracts light by a lot, e.g. diamond.
9. 3 x 108 ms-1= The speed of light in a vacuum c.
10. Refractive= To do with refraction.
11. Index= A sign or measure of something.
2. The structure of light:
Definition:
Light, or Visible Light, commonly refers to electromagnetic radiation, a portion of the
electromagnetic spectrum that can be detected by the human eye. It is usually transmitted in
waves or particles at different wavelengths and frequencies.
Features:
-Light is an electromagnetic wave that can be transmitted in waves or particles
-Light is a transverse wave, and does not need any medium to travel
-The velocity and wavelength of light changes when it travels from one medium to another
-The frequency of the light wave remains the same in all media
-Light possesses properties of both reflection and refraction
-Light gets reflected back from polished surfaces such as mirrors
-Light undergoes refraction (bending) when it travels from one transparent medium to another
-If light enters any substance with a higher refractive index (such as from air into glass) it slows
down. The light bends towards the normal line.
-If light travels into a substance with a lower refractive index (such as from water into air) it speeds
up. The light bends away from the normal line.
2
, Physics Light, Prisms & Lenses - Properties, Functions, Refraction and Key Equations
3. Interaction of light with matter:
1. Reflection:
-Definition:
Reflection occurs when light bounces off an object at the same angle as it hit the surfaces like in
glass, water or polished metal. This is called specular reflection.
-Description:
Objects can be seen by the light they emit or, more commonly, by the light they reflect. The main
source of light usually comes from the sun falling on the object. Once these light rays make contact
with the object, they reflect all subsequent light onto other surfaces. Therefore, the light can also
reach our eyes, which allows us to see certain objects. Furthermore, this process usually occurs in
the form of the law of reflection. All light hitting the object at a certain angle is reflected back at
the same opposite angle. This can include objects such as flat mirrors whose surfaces are so
smooth that light can get easily reflected.
2. Total internal reflection:
-Definition:
Total internal reflection occurs when there is complete reflection of a ray of light within passing
from a denser to a lighter medium in a such a way that the angle of incidence is greater than its
critical angle.
-Description:
The medium undergoes total internal reflection when a ray of light travels from a higher refractive
index medium to an interface with a lower refractive index material, since the only way for the
angle of refraction to be greater than the angle of incidence is for light to bend away from the
normal. Consequently, if the ray reaches the interface at an angle of incidence greater than the
critical angle for the materials involved, no part of the ray will be refracted and the entire ray will
be reflected.
3. Refraction:
-Definition:
Refraction occurs when light changes direction as it passes from one transparent substance into
another (such as from air to water).
-Description:
Refraction of light can cause objects to appear in places they shouldn't be (creating a virtual
image). This is because refraction is the breaking of light as it goes from one transparent substance
to another. Depending on the density of the two media, the direction of the light changes along
with it, due to a change in speed when entering and leaving the two media.
3
Light, Prisms & Lenses - Properties, Functions, Refraction and Key Equations
Table of Contents
1. The properties of light
1.1 Key Terminology for Light
1.2 Structure and Nature of Light (wave-particle duality, transverse wave)
1.3 Interaction with Matter
Reflection (specular and diffuse)
Refraction and its effects
Total Internal Reflection
1.4 Snell’s Law (definition, equations, applications)
2. Prisms
2.1 Key Terminology for Prisms
2.2 Definition and Structure of a Prism
3. Lenses
3.1 Key Terminology for Lenses
3.2 Lens Types and Structure
3.3 Lens Equations
Focal length, object & image distance
Magnification formulas
4. Additional questions for light and prisms
1
,Physics Light, Prisms & Lenses - Properties, Functions, Refraction and Key Equations
1. The properties of light
1. Key words for light:
1. Transparent= An object that light can pass through.
2. Ray diagram= A diagram showing the path of the light.
3. Distort= When what you see gets twisted and messed up, like fairground mirrors.
4. Refractive Index=A measure of the bending of a ray of light when passing from one medium into
another.
5. Vacuum= A space with nothing in it.
6. Medium= The material light is travelling through.
7. Critical angle= The highest angle at which refraction is observed.
8. Optically dense= Refracts light by a lot, e.g. diamond.
9. 3 x 108 ms-1= The speed of light in a vacuum c.
10. Refractive= To do with refraction.
11. Index= A sign or measure of something.
2. The structure of light:
Definition:
Light, or Visible Light, commonly refers to electromagnetic radiation, a portion of the
electromagnetic spectrum that can be detected by the human eye. It is usually transmitted in
waves or particles at different wavelengths and frequencies.
Features:
-Light is an electromagnetic wave that can be transmitted in waves or particles
-Light is a transverse wave, and does not need any medium to travel
-The velocity and wavelength of light changes when it travels from one medium to another
-The frequency of the light wave remains the same in all media
-Light possesses properties of both reflection and refraction
-Light gets reflected back from polished surfaces such as mirrors
-Light undergoes refraction (bending) when it travels from one transparent medium to another
-If light enters any substance with a higher refractive index (such as from air into glass) it slows
down. The light bends towards the normal line.
-If light travels into a substance with a lower refractive index (such as from water into air) it speeds
up. The light bends away from the normal line.
2
, Physics Light, Prisms & Lenses - Properties, Functions, Refraction and Key Equations
3. Interaction of light with matter:
1. Reflection:
-Definition:
Reflection occurs when light bounces off an object at the same angle as it hit the surfaces like in
glass, water or polished metal. This is called specular reflection.
-Description:
Objects can be seen by the light they emit or, more commonly, by the light they reflect. The main
source of light usually comes from the sun falling on the object. Once these light rays make contact
with the object, they reflect all subsequent light onto other surfaces. Therefore, the light can also
reach our eyes, which allows us to see certain objects. Furthermore, this process usually occurs in
the form of the law of reflection. All light hitting the object at a certain angle is reflected back at
the same opposite angle. This can include objects such as flat mirrors whose surfaces are so
smooth that light can get easily reflected.
2. Total internal reflection:
-Definition:
Total internal reflection occurs when there is complete reflection of a ray of light within passing
from a denser to a lighter medium in a such a way that the angle of incidence is greater than its
critical angle.
-Description:
The medium undergoes total internal reflection when a ray of light travels from a higher refractive
index medium to an interface with a lower refractive index material, since the only way for the
angle of refraction to be greater than the angle of incidence is for light to bend away from the
normal. Consequently, if the ray reaches the interface at an angle of incidence greater than the
critical angle for the materials involved, no part of the ray will be refracted and the entire ray will
be reflected.
3. Refraction:
-Definition:
Refraction occurs when light changes direction as it passes from one transparent substance into
another (such as from air to water).
-Description:
Refraction of light can cause objects to appear in places they shouldn't be (creating a virtual
image). This is because refraction is the breaking of light as it goes from one transparent substance
to another. Depending on the density of the two media, the direction of the light changes along
with it, due to a change in speed when entering and leaving the two media.
3
