Physics notes for the Grade 10 Science unit test SNC2D1 SNC2D1
Electromagnetic Radiation
Lowest energy to highest energy
Radio waves
Microwaves
Infrared waves
Visible light ROYGBV
Ultraviolet waves
Xray
Gamma
Different ways of creating light
Incandescent – way of making light from using high temperature elements
Electric discharge – when electric current glows in specific gases
Phosphorescent – absorption of UV then output visible light over time
Fluorescent – absorption of UV light then immediately outputting visible light
Chemo luminescence - process of making light through chemical reactions
Bioluminescence – animals producing light through special tissues
Tribioluminescence – producing light through rubbing crystals
Prisms
Prisms split white light into the rainbow of light
Splitting one colour will only result in a shade of that colour
Combining the rainbow with a prism can produce white light again
Terms
Light ray – the direction and straight path that light travels
Geometric optics – using light rays to determine how light behaves when it strikes an object
Incident light –light from a source that strikes an object
Transparent – almost all light passes through, objects can be see through
Opqaue – does not transmit light at all
Translucent – when an object transmits some of the light striking, it absorbs or reflects the rest
Ray Model of light
Light travels in straight lines and reflects off surfaces in different directions.
There are names for each ray, angle, and reflection.
Flat mirrors/real mirrors: have a sheet of glass before the light hits the reflecting surface
Scientific mirrors: reflecting surface first with no glass. Like how we sketch it.
Image – reproduction of an object through the use of light
Mirror – any polished surface reflecting an image
Reflection – bouncing back of an image of a surface
Plane – flat surface
Incident ray – incoming ray
Reflected ray – ray that bounces off the surface
Normal – line perpendicular to the surface
Perpendicular – right angle to surface
Angle of incidence – between incident and normal
Angle of reflection – between normal and reflection
Mirrors
Linear propagation of light: light will travel in a straight line with no interruption
Reflection
Law 1: angle of incident = angle of reflection
Law 2: incident ray and reflected ray and normal are all on the same plane
Smooth surface reflection- all reflect on the same angle and go the same direction, a full reflection can be created
Diffused surface reflection – most of the light goes in different directions, a full reflection cannot be created
A reflection seems to take place where it seems that behind the mirror there is something is not actually true because your brain picks up this information and pretends that such exists
Virtual image: the image that does not actually arrive of come at the image location
Equal perpendicular lines will create the reflection image’s depth and distance in the mirror
SALT
Size of image will be comparably smaller, normal, or larger
Altitude will be upright or inverted
Location is where the image is located
Type: Any whether it is real of virtual
Specular reflection: when all the light rays are reflected equally at the same angle and traveling the same direction. A smooth surface where an image can be seen.
Diffused reflection: rough surface where each light ray is reflected in a different direction and no clear reflected image is seen.
Locate image in a plane mirror:
Concave mirror
Center of curvature: center of circle if mirror was made into a circle
Principal Axis: horizontal line going through the center of mirror
Focus: where all the light rays meet
Locating images in concave mirror:
Rules
- light ray parallel to principal axis will reflect through F
- light ray moving in the direction of F will reflect parallel
- a light ray going through C will reflect back
- a light ray going through V follows laws of reflection
Locating a virtual image
Locating a in F
Transmitter when rays are shot at the dish from F and reflected parallel outwards
Receiver when parallel rays are shot at dish outside and reflected towards F
Convex mirror images: images on the other side, all F, C on other side
Rules:
- ray going through C will reflect on itself
- Ray going parallel will reflect upwards with F angle
- Ray aimed at focus will reflect parallel
Images formed on other side when they meet
Convex Image
Refraction:
Speed of light in vacuum: 3.00 * 10^8
Rules of refraction:
- light traveling from a less optically dens material to a more dense material will bend towards normal
- light traveling from a more dense to less dense material will bend away from normal
- light traveling parallel will go right through
Angle of incident: angle between incident ray and normal
Angle of refraction: angle between normal and refracted ray
Partial Reflection: when some light is reflected and some are refracted
Apps: pond, sunglasses, glass glare
N=v/c to determine index of refraction
Total internal refraction: when the angle of incidence is greater than the critical angle, creating refraction on the inside.
Critical angle: the angle of incidence that results in a refraction of 90 degrees
Total internal refraction:
- light travels slower in the first medium than the second
- angle of incidence is large enough so that no refraction occurs in the second medium, instead, the ray is reflected back into the first one.
Experimentally: use a ray box and point it through a medium. Move the medium at different angles gradually moving away from normal until the light is 90 degrees from incidence: that’s the critical angle
Fibre Optics: light internally reflects throughout pure glass and exits the other end
Optical telecommunication
Prisms in SLR: they reflect light up to the peek hole so the person can view the object that the lens is seeing. They reflect internally and have special refraction properties. All light coming inwards will refract out the same direction.
Diamonds:
High index: means very small critical angle means a lot of internal refraction. They will stay inside diamond and refract inside.
Apparent Depth:
Refraction of the light coming from the pencil or fish will make fish appear closer because the denser material makes the lights bend towards normal.
Mirage: light bends towards the gradient of heat and will come into the eye at a curved trajectory. When it hits the eye, the eye thinks it is straight. But it isn’t, so an inferior image of the sky appears on the ground. The light comes from the sky so it will create an image of it.
White light dispersion: different colour of lights travel at different speeds throughout prism and will result in a different direction for each. They spread out and create the rainbow.
Lenses
Diverging: thin in center, spreads light outwards
Converging: fat in center, spreads light inwards
Parallel rays are not affected
Shortcut, reduce the center angle, just use the last one: use because total angle is all that matters and is all the summarizes the actual input to result.
Principal Focus: real focus of lens
Secondary Principal focus: equivalent length on opposite side
Optical center: where optical and principal axis meets
Principal axis: axis horizontal in center of mirror
Optical axis: axis vertical and center in lens
Lateral displacement:
-thicker blocks create a more noticeable side way displacement
-thinner blocks less
thick/thin lenses create such difference and refraction
Converging lens images:
Rules:
- parallel ray going through will refract to through F
- ray going through center will be refracted parallel
- ray going through center will be straight
Diverging lens images:
Rules:
- parallel ray going through will be refracted as if it has gone through F
- a ray to pass through F’ will be will be parallel
- a light going through optical center will keep going straight
Equations:
Sign conventions
Do always same
Di negative if virtual, positive if real
Hi Positive if upright, negative if down
Ho Positive if upright, negative if down
F positive if converging, negative if down
SNC2D1 SNC2D1 SNC2D1 SNC2D1 SNC2D1
SNC2D1 SNC2D1 SNC2D1 SNC2D1 SNC2D1