Please enable JavaScript.
Coggle requires JavaScript to display documents.
PHYSICS :star: (LIGHT: :red_cross: A form of energy that can visible by…
PHYSICS :star:
LIGHT: :red_cross: A form of energy that can visible by the huma eye. Light is part of an energy continuum called electromagnetic radiation Light is made up of small packets of photons
Radio Waves: Longest Wave length, lowest frequency. Used for communications in mines, on submarines and aircrafts.
*Frequency: :check:* The rate of repetition of a wave. Energy transfered depends on the frequency of the wave
Electro Magnetic Radiation: Wave pattern of electric and magnetic fields that can travel through empty space.
Microwaves: Shorter wave lengths, higher frequency and carry more energy. Microwaves heat food by making water particles in the food vibrate.
-
Ultraviolet Rays: Carry more energy than visible light and therefore have a shorter wavelength and a higher frequency. Used to disinfect water and DNA analysis.
X-RAYS: Very high energy that can penetrate human tissues. X-rays have difficulty passing through bones making them good for medical imaging.
Gamma Rays: Extremely high energy radiation. Used to sterilize medical equipment. Doctors use short bursts to kill cancerous cells. Must wear shields to protect from radiation.
Sources of light :explode: a) Non-luminious objects are objects that do not emit their own light EX the moon. b) Luminous objects are objects that do emit their own light EX Sun
Chemical Potential Energy: A source that converts chemical energy stored within molecules into light energy. EX- Cool lights.
Heat Energy: A source which can convert heat energy within burning objects into light energy. EX- Candle, incandescent light bulb
Electrical Energy: A source that converts electric energy into light energy. EX- lightening, neon lights.
Nuclear Potential Energy: A source that converts energy stored within the nucleus of atoms into light energy through fusion or fission. EX- Atomic Bomb
Properties of Light: Rectilinear Propagation: :warning: The tendency for light to travel in straight lines esp in a homogeneous transparent medium
Transparent: Transmits light easily Translucent: Material emit some light Opaque: Absorb and reflect all light
-
Refraction: The bending of light rays as they pass through different media. This occurs due to the changes in speed of light
Index of Refraction: The amount by which a transparent medium decreases the speed of light by a number. Index of Refraction of Material= speed of light in vacuum/speed of light in medium
Optical Density: The term used to describe the relative speed of light in a given medium is "optical density" As the optical density increases, the velocity of light in that medium decreases.
Snells Law: :warning:Formula used in order to calculate the new angle that a ray will take as a beam of light strikes the interface between 2 media . **n1sin1/n2sin2*
Total Internal Reflection: When the ray bends away from the normal so much that the light does not actually escape the first medium. This means that the angle of reraction is greater than 90 . The light is being reflected back into the dense material
Critical Angle: The refracted angle is exactly 90 and therefore follows a path along the surface of the media boundary
DISPERSION: Refraction of white light into seperate wave lengths, or colours.
When sunlight passes through a raindrop some light is reflected and some is refracted twice once on entering and once on leaving. Both refractions cause the seperation of the while sunlight into colours of the rainbow.
Lens: i) Converging Lens: A lens thickest in the middle ii) Diverging Lens: A lens thickest at the ends
-
-
Concave Lenses: A diverging lens is sometimes called a concave lens. When light rays pass through a concave lens, they are refracted away from the principale axis. This means they will never meet on the other side.
Convex Lenses: Also called a converging lens. The rays always meet together. They form a real image.
*Mirrors: :check: Non luminous object with a smooth shiny surface . i) Plane mirror: :!:* Flat reflective surface is called a plane mirror. Used to look at our reflection.
ii) Curved mirrors: mirrors that are outward curved (convex mirrors) or inward-curved (concave) These images often produce very strange looking images that are different in size and shape than the object.
They have focal point: the point where light rays meet or appear to meet vertex: The middle point of a curved mirror Focal length: the distance from the vertex to the focal point of a curved mirror
-
Law of Reflection: 1) The incident ray, the normal and angle of reflection all lie on the same plane . 2) The angle of incidence always equals that angle of reflection
Virtual Image: Any image formed by rays that do not usually pass through the location of the image. EX- Reflection in a plane mirror.
-
Magnification: The measure of how much larger or smaller an image is compared with the object itself. :warning:*Magnification = image height/object height or distance of image/ distance of object