Extra Flashcards
What is monochromatic light?
- Light that has a single frequency
- A laser light is an example of a monochromatic light
What are the conditions for total internal reflection?
- The medium is entering a substance with a lower optical density
- The critical angle is exceeded
What do Optical Fibre do?
Optical fibres transmit light by total internal reflection.
What are the key features of an optic fibre?
- Core
- Cladding
- Protective Coating
What are optical fibres used for?
- Internet providers use optical fibres to set up quick and reliable internet connections.
- They can be used for endoscopy
Do optical fibre lose lots of information?
No they don’t they are able to transmit huge amounts of information with few information losses
What is a thin converging lens?
- A thin converging lens (curved piece of glass) causes parallel rays of light that pass through it to converge (come together).
- When a beam of light strikes a thin converging lens, the light is refracted twice.
What is the image produced by a conveging lens like when the object is more than two focal lengths from the centre of the lens?
- The image is real
- The image is inverted
- The image is diminished (smaller than the object)
- Examples: the eye and cameras
What is the focal length?
The focal length is the distance from the centre of the lens to the principal focus
What is the optical axis?
- The optical axis is an invisible line at 90 degrees to the face of the lens that passes through the lens’ centre.
- Light travelling along the optical axis passes through the centre of the lens without being deviated.
What is the principal focus?
- Light rays that are parallel to the optical axis pass through the lens and converge (come together) at the principal focus.
- There is one principal focus on each side of the lens as light can pass through the lens in either direction.
What is the image produced by a conveging lens like when the object is between one and two focal lengths from the centre of the lens?
- The image is real
- The image is inverted (upside down)
- The image is magnified (larger than the object)
- Examples are the projector and the photocopier
What is the image produced by a conveging lens like when the object is two focal lengths from the lens
- The image is the same size as the object
What is the image produced by a conveging lens like when the object is between the principal focus and the centre of the lens?
- The image is erect (the right way up)
- The image is Virtual
- The image is magnified
- The image is also on same side of the lens as the object
- Am example is a magnifying glass
What is the dispersion of light?
- Dispersion is the seperation of white light into a spectrum (range) of colours
- A rainbow is an example of a spectrum that is formed when sunlight is dispersed by raindrops.
What are the safety precautions taken while using X-Rays?
- Due to the dangerous nature of X-rays, exposure to X-rays should always be kept to a minimum.
- People working with X-ray equipment should always shield themselves to prevent exposure to X-rays.
- These people will place materials (metals for example lead) between themselves and the X-rays.
What are the risks of Infra-red radiation
- Infra-red radiation can cause serious skin burns if emitted from high-intensity sources.
What are the risks of microwaves (the actual wave)?
- Because humans are largely made up of water, exposure to microwaves could have a harmful effect.
What are risks of radio waves?
- At high intensities, radio waves can cause internal heating of living tissue with potentially harmful effects.
What are sound waves?
- Sound waves are longitudinal waves.
- Sound is produced by the vibration of particles in a medium (the substance that waves travel through).
- The vibrations mean that sound waves travel in a series of compressions (where the medium is squashed together) and rarefactions (where the medium is stretched apart).
