SNC2D Grade 10 Science Physics Test

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

  1. light ray parallel to principal axis will reflect through F
  2. light ray moving in the direction of F will reflect parallel
  3. a light ray going through C will reflect back
  4. 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:

  1. ray going through C will reflect on itself
  2. Ray going parallel will reflect upwards with F angle
  3. 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:

  1. light traveling from a less optically dens material to a more dense material will bend towards normal
  2. light traveling from a more dense to less dense material will bend away from normal
  3. 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:

  1. light travels slower in the first medium than the second
  2. 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:

  1. parallel ray going through will refract to through F
  2. ray going through center will be refracted parallel
  3. ray going through center will be straight

Diverging lens images:

Rules:

  1. parallel ray going through will be refracted as if it has gone through F
  2. a ray to pass through F’ will be will be parallel
  3. 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

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