Flashcards in Exam Review: Phys Deck (69):
What is refraction?
The bending or change in direction of light when it travels from one medium into another
What is the angle of refraction?
The angle between the refracted ray and the normal
What are the rules for refraction?
1. Incident Ray, refracted Ray, normal all line in same plane
2. Light bends towards the normal when the speed of light in a medium is slower
3. Light bends away from the medium when the speed of light in a medium is faster
What is the index of refraction?
The ratio of the speed of light in a vacuum to the speed of light in a medium
Can also be written as:
What does n mean in the equation n=c/v?
N= index of refraction
What does c mean in the equation n=c/v?
C= Speed of light
What does v mean in the equation n=c/v?
V= speed of light in a medium
Do you add dimensions on the end of answers using n=c/v? Why or why not?
N is dimensionless and c and v cancel eachother out
What is the critical angle?
The angle of incidence that results in an angle of refraction of exactly 90 degrees
What is total internal reflection?
Angle of incidence is greater than the critical angle & the ray is reflected back into the first medium
Images in a diverging mirror...
Useful in stores for security mirrors
How do you locate an image in a converging lens?
1. Parallel, through Focus
2. Straight through O
3. Through Focus, parallel
Draw lines from top of image
What does SALT stand for?
Describe an image in a converging mirror if the object is AT the focus
No clear image is produced
Describe an image in a converging mirror if the object is between the focus and the lens
The image is virtual
What is a plane
What is an incident Ray
An incoming Ray that strikes a surface
What is a reflected Ray?
A Ray that bounces off a reflective surface
What is the normal?
Perpendicular line to a mirror surface
What is the angle of incidence?
Angle between incident Ray and the normal
What is the angle of reflection?
Angle between reflected Ray and the normal
What does the law of reflection state?
1. Angle of incidence = angle of reflection
2. Incident Ray, reflected rays and the normal are all in the same plane
What is specular reflection?
The reflection of light off a smooth surface
What is diffuse reflection?
The reflection of light on irregular/dull surfaces
What is a virtual image?
An image formed by light coming from an apprentice light source and not actually arriving or coming from actual image location
Describe images in plane mirrors
1. The distance from the object to the mirror is the same as from the image to the mirror
2. Object-image line = perpendicular to mirror
Describe images in plane mirrors
Same size, upright, behind the mirror, virtual
What's another word for a concave mirror?
What's another word for a convex mirror?
What is the centre of curvature
The centre of the sphere whose surface has been used to make the mirror
What is the principal axis?
The line through the centre of curvature to the midpoint of the mirror
What is the vertex?
The point where the principal axis meets the mirror
What does converge mean?
To meet at the same point
What is the focus?
Where light rays parallel to the principal axis will be reflected off the mirror through a single point
What are four ways to find an image in a concave mirror?
1. Parallel and through the focus
2. Through the focus and parallel
3. Through C and back along the same line
4. To V and reflected at an equal angle
What is visible light?
Electromagnetic waves that the human eye can detect
What is the electromagnetic spectrum?
The classification of electromagnetic waves by energy
List the different wave types from lowest to highest energy
What can radio waves do?
Signals, wifi, cellphones
What can microwaves do?
Microwave ovens, telecommunications
What can infared light do?
Remotes, lasers, physical therapy
What can visible light do?
Human vision, rainbows
What can ultraviolet light do?
Skin tan/sunburn, skin cancer, kills bacteria, vitamin D
What can X-rays do?
Medical imaging, cancer treatment, security scanning
What can gamma rays do?
Cancer treatment, product of nuclear decay
What do triangular prisms do in respect to the speed of light?
They slow down the speed of light slower than what it travels in the vacuum of space and so the colours split (rainbow)
Produces its own light
Does not produce its own light
Explain incandescent lights
Light produced from high temperature
Light produced by passing electric current though a gas (neon lights)
Light produced by absorption of UV light that emits visible light over time
Immediate emission of visible light from absorption of UV light
Why are fluorescent lights better than incandescent lights?
Less energy to operate, produce less heat = less heat loss
What is bioluminescence
Light produced in living organisms by chemical reaction (little or no heat is produced)
What is triboluminescence
Light produced from friction of certain crystals
What are LED lights?
Light produced from electric current flowing in semi conductors
What is a semi conductor?
Material that allows electric current to flow in only one direction
What is an incident light?
Light emitted from a source that strikes an object
Material transmits all or almost all incident light
Material transmits some incident light but absorbs/reflects the rest
Material doesn't transmit any incident light
Does the eye open wider or close up when it's darker?
What can an eyelid be compared to?
What causes people to be near or far sighted?
When the focus is off the retina (before or after)
What is the iris?
A muscle that expands and contracts to let more/less light in through the pupil
Lens _____ is changed so the amount of bending is changed
What is the lens' job?
To make the light rays hit the same point (hopefully the retina)
Far sighted people...
Focus after the retina