P3.1.5 Other Applications Using Light Flashcards
What is a laser?
An intense narrow beam of light that spreads out very little.
Give 3 uses of lasers as an energy source.
Cutting through materials (such as metal)
Burning (e.g. laser engraving)
Cauterising
How could lasers be used in medicine?
To destroy damaged tissue or to stop bleeding (cauterising).
Laser eye surgery - to precisely cut the cornea, altering its shape to correct a person’s vision.
What is the critical angle?
The angle of incidence beyond which rays of light are not refracted but totally reflected.
How does total internal reflection work?
A ray of light hits a more dense medium and the angle of incidence is greater than the critical angle so all of the light is reflected and instead of being refracted.
How do optical fibres work?
Light that enters the optical fibre at one end is totally internally reflected all the way along so that it emerges at the other end - even when the fibre is bent.
What is an optical fibre?
A very thin rod of high quality glass.
What is an endoscope?
An instrument used in medicine to examine the inside of the body which uses a bundle of optical fibres - some which carry light into the body and some which carry reflected light back out.
How does the refractive index of a material affect the critical angle?
Lower refractive index = higher critical angle.
Higher refractive index = lower critical angle.
