Zusammenfassung der Ressource
Light KS3 Y7
- Lumination
- Luminous means a light source that emits light
- Illuminated means an object on which light shines and from which light may be reflected
- Opaque is an object where no light can pass through
- All light is absorbed or reflected
- Translucent is an object where some light passes through
- It absorbs and reflects some light
- Transparent means an object where all or most light passes through
- Very little or no light is absorbed or reflected
- Shadows
- Point source is where light rays are emitted radially.
- Non-point source is where rays from different part of the source form different overlaping shadow.
- Umbra is a complete shadow (all rays blocked).
- Penumbra is partial shadows, (some rays blocked).
- Pin-hole camera
- The image will be inverted
- Small pin hole: focus but dimmed image
- Large pin hole:unfocused but brighter image
- Rays pass through the middle of the gap.
- If there are two gaps, then there will be two images
- Reflection
- When light shines on an object, it is either transmitted, absorbed or reflected
- A normal mirror is a flat plane and a regular reflector
- An uneven shiny surface is a diffuse reflector
- A line separates line into two and is called a normal line
- The incident ray is the same angle as the reflected ray
- If there was an odd number of mirrors, the image would be laterally inverted, upside down
- The virtual ray is on the opposite side of the mirror and is in line with the reflection.
- The virtual image is the image on the other side of the mirror
- The visible spectrum
- White light is a mixture of all the colours in the visible spectrum
- Richard Of York Gave Battle In Vain (Red , orange, yellow, green, blue, indigo, violet)
- When a white light travels through a prism it splits into its component colours
- Each component bends through a different angle.
- Red bends the least and violet bends the most
- Some materials only reflect or transmit certain colours and asborbs the rest
- The bending is called refraction and the splitting is called dispersion
- In additive, red, green and blue are the primary colours
- Yellow, magenta and cyan are the secondary and altogether the secondary colours make white.
- In the subtractive, it is the opposite and all of them create black.