SNC2D Physics Test #1 Flashcards
What is light?
It is any kind of Electromagnetic Wave caused by vibrating atoms or electrons.
What is an Electromagnetic Wave?
They are light and are caused by vibrating atoms or electrons.
What is the visible spectrum?
It is the narrow range of light which is visible to the human eye.
What is incandescence?
It is heating things up like a flame or light bulb.
What is Fluorescence?
It is exciting atoms with one form of energy causing them to immediately produce another – tube lights.
What is Phosphorescence?
It is exciting atoms with one form of energy causing them to slowly produce another – ‘glow in the dark’
What is Chemiluminescence?
It is production of a light because of a cold chemical reaction (not burning) – glow sticks – in living things this is called Bioluminescence.
What is Electroluminescence?
It is produced when electrons fall into orbitals of atoms in LED semiconductors.
For an object to be Luminous means that…
The object produces its own light.
If an object is non-luminous it means that…
The object just reflects light, doesn’t give it off.
What is the speed of light and what is its symbol?
Its speed is 3.0 x 105 km/s (about 300 000 kilometers per second). It is such an important speed that it is given its own letter as a symbol c.
What does Rectilinear Propagation mean?
It means that light only travels in straight lines - as long as nothing gets in its way, that is.
What does the acronym SALT stand for? What do these things describe?
Size
Attitude
Location (position)
Type
These four things describe the way that light behaves.
What is a real image?
It is an image which can be projected on a screen.
What is a virtual image?
This is a image that appears only in the interacting surface (e.g. the mirror).
Define what size refers to (in reference to describing images with SALT).
Is the image the same size, larger or smaller than the original object?
Define attitude/orientation.
Define location/position.
The image may appear the same distance, nearer or farther away from the interacting surface than the original object. (“Objects in the rear view mirror are closer than they appear.”)
What are the two types of images?
Real and virtual.
What are the three types of mirrors? Explain each.
- Spherical - If the curve was extended it would form a ball.
- Parabolic - the curve was extended, the ends would never meet.
- Random - like a funhouse mirror.
What is a ray?
It is just a vector (line with an arrow) that shows the direction something is travelling.
What does the Law of Reflection state?
This law states that the Angle of Incidence equals the Angle of Reflection.
What is the normal line?
This is a line drawn perpendicular (at right angles) to the reflecting surface at the point where the reflection takes place. The angles of incidence and reflection are measured against it.
Define transparent.
This means that light can pass through an object.
Define translucent.
This means that light can pass through and object but lose intensity.
Define opaque.
This means that light cannot pass through the object.
What does the term “plane” mean when talking about mirrors?
It simply means it is a flat mirror.
What are the two main types of mirrors?
Plane or curved.
What is the focal point?
This is the point where light rays tend to converge from distant light sources. It is located exactly halfway between the surface of the mirror and the its curvature.
What are prisms?
These are blocks of clear glass or plastic.
What are prisms used for?
These can be used to show how light changes direction. Newton used a prism to bend light enough to make it break into individual colours.
What are lenses?
These are just prisms with curved surfaces. They bend light through refraction just like regular prisms, with none of the distortion.
What is refraction?
This is when light enters a new material it changes speed. If the light enters at an angle other than 90 degrees (perpendicular) to the surface this causes the light to change its direction of travel.
Do the rays of light that hit a concave mirror converge or diverge?
The rays of light will diverge in this type of lens.
Do the rays of light that hit a convex mirror converge or diverge?
The rays of light will converge in this type of lens.
In a plane mirror, a line perpendicular to the surface of the mirror is:
a) a ray
b) the normal
c) a tangent
d) the same distance behind as in front
b) the normal
A concave mirror is:
a) a domed mirror
b) a plane mirror
c) a useless mirror
d) used on satellite dishes
d) used on satellite dishes
When white light is separated into its component colours through dispersion, which colour is not present?
a) red
b) orange
c) yellow
d) blue
e) violet
f) brown
f) brown
In a plane mirror, all images are:
a) real
b) imaginary
c) laterally inverted
d) upside down
e) both b and c
e) both b and c (imaginary/virtual and laterally inverted)
Another example of an electromagnetic wave, other than light, is:
a) water wave
b) sound wave
c) radio wave
d) permanent wave
c) radio wave
This kind of light is produced when atoms absorb one form of energy and release it as another form immediately.
a) incandescence
b) fluorescence
c) phosphorescence
d) chemiluminescence
b) fluorescence
This kind of light is produced by hot things
a) incandescence
b) fluorescence
c) phosphorescence
d) chemiluminescence
a) incandescence
- When describing at the characteristics of an image you have to consider:
a) size b) attitude c) location d) type e) all of the previous
b) the normal
- In a plane mirror, a line perpendicular to the surface of the mirror is :
a) A ray b) the normal c) a tangent d) the same distance behind as in front
b) the normal
- A convex mirror is a:
a) convergent mirror b) dish shaped c) dome shaped d) used on satellite dishes
c) dome shaped
- Plane mirrors don’t have which of the following?
a) focal point b) centre of curvature c) principle axis d) all of the previous
d) all of the previous
- Which of the following is not an electromagnetic wave:
a) radio b) infrared c) ultraviolet d) sound e) gamma
d) sound
- When describing the characteristics of your image in a plane mirror, which of the following words are correct:
a) real b) inverted c) laterally inverted d) larger than life e) scary
c) laterally inverted
- In a curved mirror, a line joining centre of curvature to the surface of the mirror at the vertex is called the:
a) Incident ray b) principle axis c) reflected ray d) focal length
b) principle axis
- If a light ray travelling along the Normal, enters a more dense transparent medium, it will:
a) maintain the same velocity b) speed up c) slow down d) reflect
c) slow down
- If a light ray enters a more dense transparent medium at an angle, it will:
a) continue in the same direction b) turn away from the normal
c) turn towards the normal d) reflect if the angle is greater than the critical angle
d) either b or d
c) turn towards the normal
- A concave mirror is a:
a) convergent mirror b) divergent mirror c) useless mirror d) used on car side mirrors
a) convergent mirror
- A lens can be:
a) double concave b) double convex c) single concave d) single convex e) any of the previous
e) any of the previous
What is the Law of Refraction?
When light enters a new substance, it bends towards the normal when the new substance is more dense, and away from the normal when the new substance is less dense.
What kind of a wave is a light wave? Give a brief description.
Light is an electromagnetic wave with electric and magnetic components running perpendicular to each other. (electric - vertical, magnetic - horizontal)
When light enters a more dense substance, does it bend towards or away from the normal?
Towards the normal.
What are 6 other kinds of electromagnetic light other than visible light?
Radio waves, microwaves, infrared, ultra-violet rays, x-rays, gamma rays, cosmic rays.
What are radio waves used for? How?
They are used for radio stations, with all their differrent frequencies. The waves are picked up by a long wire that must be at least half the length of the wave.
What are microwaves used for? How?
Cell phones and satellite dishes: an even smaller antenna than for radio, but works in the same way. A ‘cell’ phone must be near a tower to send and receive data. Satellite dishes for TVs, satellite phones and satellite radio (sirius, xm) receive signals from satellites directly.
What does LASER stand for?
Light Amplified by Stimulated Emission of Radiation
What do the light waves emitted by a laser look like?
The waves are all aligned/parallel to each other.
What is the critical angle?
This is the incident angle at which light enters a dense substance and when this light tries to exit, it refracts at an angle of 90º to the normal.
What happens when light entering a dense substance enters at an angle that exceeds the critical angle?
The light will reflect back into the dense substance. The interface (common boundary/surface) of the substance will in fact become almost a perfect mirror and Total Internal Reflection occurs.
What is Total Internal Reflection?
This is when the incident angle of light exceeds the critical angle, so that the light exiting the substance refracts at an angle greater than 90º in such a way that it doesn’t actually refract at all, but instead the surface of the substance acts like an almost perfect mirror, and the light reflects.
What are some uses of Total Internal Reflection?
It is useful in Fibre Optics. It is also used in high-quality optical devices like binoculars and CD/DVD/Blu-ray players.
How is Total Internal Reflection used in Fibre Optics? What is it used for?
Laser light is shone in one end of the optical fibre and it reflects around in the thread until it emerges from the other end.
It is used in modern telecommunications.
