Light Flashcards
Density:
The amount of molecules in an area
Refraction
When light passes through and reflects of water and slows down and distorts objects
Transverse wave
Waves that move up and down at a 90 degree angle
Longitudinal wave
Compression waves that go sideways instead of up and down like a slinky/spring.
Velocity
The speed of something
Frequency
the rate per second of a vibration constituting a wave, either in a material (as in sound waves), or in an electromagnetic field (as in radio waves and light)
Wavelength
the distance between successive crests of a wave, especially points in a sound wave or electromagnetic wave.
Crest
Crests and troughs in a transverse wave. (Up and down)
Transparent
allowing light to pass through so that objects behind can be distinctly seen.
Translucent
(of a substance) allowing light, but not detailed shapes, to pass through; semi-transparent.
Opaque
not able to be seen through; not transparent.
Refraction
the fact or phenomenon of light, radio waves, etc. being deflected in passing obliquely through the interface between one medium and another or through a medium of varying density.
Bending
shape or force (something straight) into a curve or angle.
Total internal reflection
the complete reflection of a light ray reaching an interface with a less dense medium when the angle of incidence exceeds the critical angle.
Light
the natural agent that stimulates sight and makes things visible.
What happens when the medium changes
More dense to less dense = away from the medium
Less dense to more dense = towards the medium
Fact:
Angle of incidence > critical angle
Prism
A triangular object that refracts light. Making a rainbow. It is translucent
Dispersion
the separation of white light into colours or of any radiation according to wavelength.
Which colour has a higher frequency.
Red has a lower frequency, violet has a higher frequency
What happens when light hits an object:
It either gets absorbed, reflected, refracted or passes through
Give examples of transperant
Window, magnifying glass, clear plastic bottle
Give some examples of translucent
Foggy glass, frosty window, tea strainer
Give some examples of opaque
Desk, phone, brick, loaf of bread
Define: Total internal reflection
when the angle of incidence exceeds the critical angle and bends so far from the normal that it reflects of the less dense material.
Critical angle:
the angle of incidence beyond which rays of light passing through a denser medium to the surface of a less dense medium are no longer refracted but totally reflected.
When does total internal reflection occur
When the density that the medium is in becomes smaller when the light passes through.
What happens when light travels through diamond (more dense) to air (less dense).
Total internal reflection occurs and light bends away from the normal.
What happens when light travels through air (less dense) to diamond (more dense) ?
The light bends towards the normal
Medium
The substance which either: light travels through, absorbs, reflects or refracts
Refracted ray
A ray which has been bent due to refraction
Ray of incidence
The ray that is going towards the medium.
Reflected ray
The ray that is going away from the medium
Angle of incidence
The angle in between the normal and the ray of incidence.
The angle of reflection
The angle that is in between the ray of reflection and the normal.
What colour has the shortest wavelength and highest frequency?
Violet
What colour has the lowest frequency and the longest wavelength?
Red
What colour is most refracted?
Violet
What colour is least refracted?
Red
What is an image in a mirror?
A virtual image, laterally reflected and is not magnetised.
What is the formula for velocity?
Velocity= frequency X wavelength
Iris
a flat, coloured, ring-shaped membrane behind the cornea of the eye, it controls the amount of light that comes into the eye by changing the size of the cornea, people have different colours.
Cornea
The transparent layer forming the front of the eye. It protects the iris, pupil and the anterior chamber. It has no blood vessels
Pupil
Pupil: The opening of the iris. The pupil tends to open (dilate) and close (constrict) to control light getting inside the eye. But it is really the iris that is the prime controller of light. They work together.
Anterior chamber:
The anterior chamber is the fluid-filled space inside the eye between the iris and the cornea’s innermost surface. Aqueous humor is the fluid that fills the anterior chamber.
Aqueous humour:
It is a transparent, watery fluid held in the anterior. It helps the eye keep its shape.
Vitreous humour:
It makes up a large portion of the eyeball. It is a clear gel-like substance that occupies the space behind the lens and in front of the retina at the back of the eye.
Sclera:
The white outer layer of the eyeball. It acts like a supporting wall of the eyeball, and is made up of conjunctiva, a clear mucus membrane that helps lubricate the eye. It is thickest in the area surrounding the optic nerve. It is clear and is ‘continuous’ like the Cornea so you can still see.
Lens:
The lens is at the front of the eye and is clear. Its job is to focus the light rays that pass through it and send it onto the retina in order to create clear images of objects that are positioned at various distances.
Ciliary body
Made up of 3 parts: ciliary muscle, which controls the shape of the lens, and the ciliary epithelium, which produces the aqueous humor. The ciliary body is part of the uvea, the layer of tissue that delivers oxygen and nutrients to the eye tissues.
Choroid
the vascular layer of the eye, containing connective tissue, and lying between the retina and the sclera
Retina
It is a layer at the back of the eyeball that contains cells that are sensitive light, which trigger nerve impulses that pass via the optic nerve to the brain, where a visual image is formed.
Fovea centralis
It is a small, central pit composed of closely packed cones in the eye. It is located in the retina, it detects colours.
Optic nerve
It transmits impulses to the brain from the retina at the back of the eye, this creates an image.
Photoreceptors
They detect the amount of light present during vision. There are 2 types of photoreceptors in the retina: rods and cones.
What are rods?
Rods are one type of photoreceptors they pick up on light differences, movement and shapes. They are efficient in dimly lit rooms, they are poor at colour vision. They are located in the retina.
What are cones?
Cones are highly sensitive to red, blue and green. They are located in the retina. They receive light well but don’t work well in a dimly lit room. They then send messages to the brain and that is how we depict colour.
Suspensory ligament
It is a series of thin fibres that connect the ciliary body of the eye with the lens, holding it in place.
Optic disk AKA. The blind spot.
It is a raised disc on the retina at the point of entry of the optic nerve, it lacks visual receptors therefore seclude for vision from this area.
Name the items on the electromagnetic spectrum in order from longer to shorter wavelengths
AM Radio, aircraft communication, microwave, TV remote, infrared, -VISIBLE LIGHT-, Uv rays, airport security scanners, PET scanner, Terrestrial waves, Gamma flashes.
Give examples of concave mirrors
Torches, car headlights, guiding aircrafts and boats, satellites
Give some examples of convex mirrors.
Glass lenses, sunglasses, street lights, ceiling dome mirrors, on corners of roads, corners of supermarkets.
What type of wave is light?
It is a transverse wave
What is a transverse wave?
Light is a transverse wave, it moves up and down at 90° angles.
What is crest and trough?
The crest is the highest point that the wave rises to. The trough is the lowest point.
What is the term for angles in terms of theta?
θ°= angle of incidence θ'°= angle of reflection θ^r= angle of refraction θ^r2 = second angle of refraction (very rare)
When rainbows are formed at what angle from the sunlight is red and blue formed?
Red is formed at 42° and blue is formed at 40°
What do you call waves have that goes through the middle of it?
An Equilibrium
What is the law of reflection?
The angle of incidence = angle of reflection
