(SNC2D1) Physics: Light and Geometric Optics

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(SNC2D1) Physics: Light and Geometric Optics

1. UNIT 11: PHENOMENA OF LIGHT 1 - MIRRORS AND REFLECTION

1.1. TYPES OF MIRRORS

1.1.1. MIRROR: a non-luminescent object with a smooth shiny surface that reflects light in such a way that images form

1.1.1.1. PLANE MIRRORS: any mirror that has a flat reflective surface; light bounces off these mirrors in a similar way that a hockey puck bounces off the boards; the ray moving towards the mirror is known as the incident ray whereas the ray reflecting off the mirror is known as the reflected ray

1.1.1.2. CURVED MIRRORS: mirrors that are curved outward (convex) or inward (concave) where the images produced often appear strange looking and different from the object in size and shape

1.1.1.2.1. CONVEX MIRRORS reflect light away in multiple direction from the mirror; produce virtual images; all the light seems to come from the virtual focal point

1.1.1.2.2. CONCAVE MIRRORS reflect light towards one point, the focal point

1.1.1.2.3. VERTEX: the middle point of a curved mirror

1.1.1.2.4. FOCAL LENGTH: the distance from the vertex to the focal point

1.2. THE LAWS OF REFLECTION

1.2.1. 1- the incident ray, the normal and the reflected ray all lie on the same plane

1.2.2. 2- the angle of incidence is equal to the angle of reflection

1.3. DESCRIBING IMAGES

1.3.1. SIZE: the image can be larger or smaller than the object; this is measured in magnification

1.3.2. ORIENTATION OR ATTITUDE: the image can be upright or inverted in comparison to the object

1.3.3. LOCATION: the image can be in front of the mirror or behind it

1.3.4. TYPE: Real images can be projected on a screen and are in front of the mirror, Virtual images can only be seen by looking at or through the optical device as the image is behind the mirror

1.4. MAGNIFICATION

1.4.1. Can be calculated when dividing the image height by the height of the object equals dividing the image distance by the object's distance

3. UNIT 10: THE NATURE OF LIGHT

3.1. WHAT IS LIGHT?

3.1.1. THE ELECTROMAGNETIC SPECTRUM

3.1.1.1. LIGHT: the form of energy that can be observed with the human eye; it is part of the electromagnetic spectrum

3.1.1.2. ELECTROMAGNETIC SPECTRUM: TV and radio waves, microwaves, infrared waves, visible light, ultraviolet rays, X-rays, gamma rays

3.1.2. THE WAVE MODEL OF LIGHT

3.1.2.1. WAVES: energy in the electromagnetic spectrum travels as waves

3.1.2.2. CHARACTERISTICS OF WAVES

3.1.2.2.1. CREST: highest point of the wave

3.1.2.2.2. TROUGH: lowest point of the wave

3.1.2.2.3. REST POSITION: no wave

3.1.2.2.4. WAVE LENGTH: distance from the same place in consecutive waves; can run from crest to crest or trough to trough; symbolized by what looks like an upsidedown y

3.1.2.2.5. AMPLITUDE: height or depth of the wave from rest to crest or rest to trough

3.1.2.2.6. FREQUENCY: the rate of repetition of the wave

3.1.3. WHAT IS LIGHT MADE OF?

3.1.3.1. THE 6 COLOURS THAT MAKE UP WHITE LIGHT

3.1.3.1.1. RED: bends the least; frequency is 4.3x10^14 Hz; Wavelength is 700 nm

3.1.3.1.2. ORANGE: frequency is 5.0x10^14 Hz; Wavelength is 600 nm

3.1.3.1.3. YELLOW: frequency is 5.2x10^14 Hz; Wavelength is 580 nm

3.1.3.1.4. GREEN: frequency is 5.7x10^14 Hz; Wavelength is 550 nm

3.1.3.1.5. BLUE: frequency is 6.4x10^14 Hz; Wavelength is 450 nm

3.1.3.1.6. VIOLET: bends the most; frequency is 7.4x10^14 Hz; Wavelength is 400 nm

3.2. PRODUCING VISIBLE LIGHT

3.2.1. SOURCES OF LIGHT

3.2.1.1. LUMINIOUS AND NON-LUMINOUS OBJECTS

3.2.1.1.1. LUMINOUS OJECTS: produce the light they give off, e.g. the Sun

3.2.1.1.2. NON-LUMINOUS OBJECTS: do not produce their own light, e.g. the moon

3.2.1.2. ENERGY

3.2.1.2.1. CHEMICAL POTENTIAL ENERGY: a source which converts chemical energy stored within its molecules into light energy; often call "chemiluminescence" living organisms who produce light in this way are known as "bioluminescence"

3.2.1.2.2. HEAT ENERGY: a source which converts heat energy within objects burning to produce light; called "incandescence" and produces a great deal of heat

3.2.1.2.3. ELECTRICAL ENERGY: a source which converts electrical energy to light energy; you can get light energy by passing electricity through a gas such as neon and this energy can be associated with incandescence, fluorescence, or phosphorescence.

3.2.1.2.4. NUCLEAR POTENTIAL ENERGY: a source which converts energy stored within the nucleus of atoms into light energy through fission or fusion (e.g. atomic bombs)

3.2.2. LIGHT SOURCES

3.2.2.1. INCANDESCENCE

3.2.2.2. FLUORESCENECE

3.2.2.3. PHOSPHORESCENCE

3.2.2.4. CHEMILUMINESCENCE

3.2.2.5. TRIBOLUMINSCENCE

3.2.2.6. ELECTRIC DISCHARGE

3.2.2.7. ORGANIC LIGHT-EMITTING DISPLAY

3.2.2.8. PLASMA DISPLAY

3.2.2.9. LIQUID CRYSTAL DISPLAY

3.3. THE PROPERTIES OF LIGHT

3.3.1. RECTILINEAR PROPAGTION

3.3.1.1. TRANSPARENT: transmit light freely - light passes right through

3.3.1.2. TRANSLUCENT: transmit some light, absorbs and reflects some; cannot be seen right through

3.3.1.3. OPAQUE: absorb and reflect all light

3.3.2. RAY MODEL DIAGRAMS: used to show the path that light travels in different circumstances; arrows point in the direction that light is travelling

3.3.3.1. UMBRA: darkest part of the shadow

3.3.3.2. PENUMBRA: parts of the shadow where some light falls

4. UNIT 12: PHENOMENA OF LIGHT 2 - LENSES AND REFRACTION

4.1. REFRACTION: the change in direction of light when it travels between two mediums; occurs because the light is changing speed

4.1.1. LIGHT travels at a speed of 3.00x10^8 m/s in a vacuum with a refractive index of 1.00

4.1.2. INDICES OF REFRACETION

4.1.2.1. OPTICAL DENSITY: the relative speed of light in a given medium; as it increases the speed of light increases

4.1.2.2. THE INDEX OF REFRACTION: the amount by which a transparent medium decreases the speed of light; the more optically dense a medium is, the more it will slow light down

4.1.2.2.1. Calculation the index of refraction uses the equation n=Va/Vg=c/v

4.1.3. SNELL'S LAW states that n equals the indices of refraction for the different media and θ1 is the angle of incidence for one while θ2 is the angle of refraction for the other

4.1.3.1. calculated by the equation n1sinθ1=n2sinθ2

4.1.3.1.1. θ1 = angle of incidence

4.1.3.1.2. n1  = first refractive index

4.1.3.1.3. θ2 = angle of reflection

4.1.3.1.4. n2 = second refractive index

4.2. LENSES

4.2.1. CONVERGING LENSES: thickest in the middle

4.2.2. DIVERGING LENSES: thickest at the ends

4.2.3. OTHER LENS TERMINOLOGY

4.2.3.1. PRINCIPAL AXIS: an imaginary line drawn through the optical centre perpendicular to both surfaces

4.2.3.2. AXIS OF SYMMETRY: an imaginary vertical line drawn through the optical centre of a lens

4.2.3.3. PRINCIPAL FOCUS (focal point): a point onto which collimated light parallel to the axis is focused

4.2.3.4. FOCAL LENGTH (f): the distance from the axis of symmetry to the principal axis measured along the principal axis

4.2.3.5. OPTICAL CENTRE: a point on the axis that is located in such a way where light passes through the lens without refracting and suffers no deviation whatsoever that may be within, without or on either surface

4.2.4. THE THIN LENS EQUATION: used to identify the focal length, distance of the object and the distance of the image

4.2.4.1. 1/f=1/do+1/di

4.2.4.2. can be used with the magnification equation (hi/ho=di=do) to figure out the magnification of the lens