Light Flashcards
What is an object that gives off its own light?
Luminous Object
Whats an object that doesn’t give off its own light?
Non luminous object
Describe how light travels
In straight lines in all directions at 300,000,000 meters per second
State the Law of Reflection
The angle of reflection is equal to the angle of incidence
Describe the effect that a concave curved mirror has on parallel rays of light
The reflected light rays converge and come to a focal point
Describe the effect that a convex curved mirror has on three parallel light rays
The reflected light rays diverge
What is total internal reflection
Total internal reflection is when light travels through a transparent material such as an optical fibre by reflecting off the inside surface
Provide three examples of uses of fibre optics
Surgical uses such as a Laparoscopy. Transmiting data at 200MPS and can also be used to see hard to reach places such as pipes and sewers.
What happens when light enters a glass block
It refracts towards the normal as it enters the block and away from the normal as it exits the block
What is the Law of refraction?
The angle of refraction is smaller than the angle of incidence when it goes from air into glass
What causes long or short sight?
It is caused by the eyeball being too long or short
If someone’s eyeball is too long where is the image focused?
The image is focused in front of the retina. This means they are short sighted.
If someone’s eyeball is too short, where is the image focused?
The image is focused behind the retina. This means the person is long sighted.
What is the definition of incidence ray?
Its a ray of light that is going to a mirror or surface.
What is the angle of incidence?
The angle of incidence is the angle between the incidence ray and the surface normal.
What’s the reflected ray?
The reflected ray is the ray coming from the mirror or surface
What is the angle of reflection
Its the angle between the reflected ray and the surface normal
What is the surface normal
Its the dotted line at a 90° angle to the surface
What are the colours in the visible light spectrum in order
Red, Orange, Yellow, Green, Blue, Indigo, Violet
Explain Newtons experiment to find the visible colour spectrum
Newton used a prism to disperse the beam of white light into the diffrent colours of the light spectrum.
What are the three primary additive colours
Red, Green and Blue
What colour do you get when you combine red and green
Yellow
What colour do you get when you mix green and blue?
Cyan
What colour do you get when you mix blue and red?
Magenta
What colour do you get when you mix red,green and blue
White
List the Electro Magnetic spectrum from shortest to longest wave length
Gamma, X- ray, UV, Visible, Infared, Microwave, Radiowave
State a use of radio waves
Radio and TV
State a danger of radio waves
None
State a use of microwaves
Cooking, signals, phones
State a danger of microwaves
Heat body tissue
State a use of infrared light
Night vision, security, remote controls
State a danger of infrared
Skin burns
State a use of visible light
Cameras, seeing
State a danger of visible light
None
State a use of ultraviolet light
Sanatisation,Sunbeds, security
State a danger of UV light
Burns, skin cancer, damages eyes
State a use of x-rays
X-ray machines
State a danger of xrays
Damage cells, cancer
State a use of gamma rays
Sterelising things, cancer therapy
State a danger of gamma rays
High exposure kills cells
What is the difference between concave and convex lenses
A concave lens is skinnier in the middle than at the sides, a convex lens is the inverse.
What is the approximate size of a radio wave
Buildings/10^3m
What is the approximate size of microwave rays
Humans/10^-2m
What is the approximate size of infrared light
Needle point/10^-5m
What is the approximate size of visible light
Protozoans/0.5x10^-6m
What is the approximate size of UV light
Molecules/10^-8
What is the approximate size of x-rays
Atoms/10^-10m
What is the approximate size of gamma rays
Atomic nuclei/10^-12m
