Physics Test: Electromagnetic Radiation and Lenses

SNC2D Grade 10 Science Physics Test Electromagnetic Radiation Lowest energy to highest energy Radio waves Microwaves Infrared waves Visible light ROYGBIV Ultraviolet waves Xray Gamma Different ways of creating light Incandescent – way of making light from using high temperature elements Electric discharge – when electric current flows in specific gasses 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 Triboluminescence – producing light through rubbing crystals Prisms Prisms split white light into the rainbow of light Splitting one color will only result in a shade of that color 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 Opaque – 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 dense 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 peephole 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 the 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 colors 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 that 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