Physics (Exam)

Front 1

How do all sources of light emit light?

Back 1

Light is the result of electrons moving between energy levels in an atom, called shells. When something excites an atom, like a collision with another atom or a chemical electron, an electron absorbs the energy, & goes to a higher-level shell. The boost is short & the electron falls back down to the lower level, emitting its extra energy in the form of an electromagnetic energy packet called a Photon. The wavelength depends on the distance of the electron’s fall. Photons with wavelengths in the visible spectrum form colours we can see.

Front 2

Define fluorescence.

Back 2

Light that is emitted during exposure of the source to ultraviolet light.

Front 3

Define incadescence.

Back 3

Light emitted from a material because of high temperatures.

Front 4

Define luminescence.

Back 4

The emission of light by a material or an object that has not been heated, for example fluorescence.

Front 5

Define phosphorescence.

Back 5

Light that is emitted due to exposure of the source to ultraviolet light, and that continues to be emitted for some time in absence of ultraviolet light.

Front 6

Define chemiluminescence.

Back 6

Light that is produced by a chemical reaction without a rise in temperature.

Front 7

Why are incandescent lights inefficient?

Back 7

Because only about 5% of the electrical energy used in the bulb becomes light, while the remaining 95% is lost as heat.

Front 8

What is a reflection?

Back 8

The change in direction of a wave when it reaches a surface and bounces off that surface.

Front 9

What is a medium? A ray?

Back 9

Medium: The substance through which light travels.

Ray: A straight line with the arrowhead that shows the direction in which light waves are travelling.

Front 10

What is Fermat's principle?

Back 10

Fermat's principle predicts the path of light will take after reflecting from a surface or passing though more than one medium.

Fermat's Principle: light follows the path that will take the least time.

Front 11

What are the laws of reflection?

Back 11

1) The incident ray, the reflected ray, and the normal ray always lie on the same plane.

2) The angle of reflection,

Front 12

Describe the electromagnetic spectrum. What type of visible light has the lowest energy ? What type of visible light has the shortest wavelength?

Back 12

The electromagnetic spectrum is a diagram that illustrates the range, or spectrum, of electromagnetic waves, in order of wavelength or frequency.

Lowest energy (longest wavelength): red

Shortest wavelength (highest energy) : voilet

Front 13

Describe the LOST characteristics.

Back 13

Location: closer than, farther than, or same distance as the object to the mirror

Orientation: upright or inverted

Size: same size, larger than or smaller than the object

Type: real image or virtual image

Front 14

What type of mirror or lens always gives a virtual image that is upright ad the same size?

Back 14

A plane mirror.

Front 15

What is the mirror equation?

Back 15

Front 16

What is the magnification equation?

Back 16

Front 17

What is a spherical aberration?

Back 17

Irregularities in an object in a curved mirror that result when reflected rays from the outer parts of the mirror do not go through the focal point.

Front 18

Define refraction.

Back 18

The bending of light as it travels, at an angle, from a material with one refractive index to a material with a different refractive index.

Front 19

What does Fermat's principle say about refraction?

Back 19

It's used to find the exact path of light as it travels from one medium to another. Fermat's principal says light follows the path that takes the least time. In a single medium the path taking the least time is a straight line. When travelling from one medium to another, the path that takes the least time is not a straight line.

Front 20

What is a refracted ray? An angle of incidence?

Back 20

Refracted ray: The ray that is bent upon entering a second medium.

Angle of incidence: The angle between the normal and a refracted ray.

Front 21

What happens when a ray moves from a slower medium to a faster medium?

Back 21

The reflected ray bends away from the normal, therefore resulting in a greater angle of refraction.

Front 22

What happens when a ray moves from a faster medium to a slower medium?

Back 22

The reflected ray bends towards the normal therefore resulting in a smaller angle of refraction.

Front 23

What is the formula used to calculate the index of refraction?

Back 23

n : index of refraction

c : speed of light in a vacuum

(3.00 x 10^8 m/s)

v : speed of light in a medium

Front 24

Explain three possible scenarios when light refracts from water to air.

Back 24

1) When the angle of incidence < critical angle, both reflection and refraction occurs at the boundary between the two media.

2) When the angle of incidence increases, the angle of refraction will eventually reach 90 degrees. At this angle of incidence, the refracted ray lies along the boundary between the two media (called the critical angle)

3) When the angle of incidence is larger than the critical angle, all the light is reflected back into the first medium. This is called total internal reflection.

Front 25

Why do we see rainbows?

Back 25

A rainbow forms when sunlight enters a water droplet and refracts, reflects off the inner surface of the droplet, and then refracts again when leaving the droplet. The two refraction's result in the dispersing of light. (ROYGBIV)

Front 26

Why do we see shimmering?

Back 26

It's caused by the refraction of light in unevenly heated air. When light travels through air at different temperatures it refracts because hot air is less dense than cooler air. Shimmering is the apparent movement of objects in hot air over objects and surfaces.

Front 27

What is spherical aberration with lenses?

Back 27

If a lens is very thin; the effect isn't noticeable. For thick lenses, only light rays that pass through the lens near the principal axis meet at the focal point and give a sharp image.

Front 28

What is chromatic aberration?

Back 28

The dispersion of light through a lens.

Front 29

How can spherical and chromatic aberration be corrected?

Back 29

It can be partially corrected by combining one or more lenses;especially if they're made with materials of different indices of refraction.

Front 30

What is a lens?

Back 30

A transparent object with at least one curved side that causes light to refract.

Front 31

What happens to a parallel light ray when it passes through a converging lens? Diverging?

Back 31

Converging: The parallel light rays come together and converge to a common point.

Diverging: The parallel light rays spread away from a common point and diverge.