Assignment 14 – Reflection and Refraction. Light Waves. Light Emission – Flashcards

Incident light makes the electrons oscillate. The electrons then emit light or absorb the light and convert it to heat.

Light takes the quickest path in going from one place to another.

The angle of incidence equals the angle of reflection.

About 4%

Astigmatism is caused when the cornea has a different radius of curvature in one direction compared to another. It is cured by adding a lens with a different radius of curvature in two different directions.

The angle of refraction is smaller than the angle of incidence, other than when the flashlight is on the normal line.

The angle of refraction increases.

The angle of refraction is greater than the angle of incidence.

The angle of refraction increases.

the angles are the same

Yes. It is as if the curved mirror is made of many small plane mirrors at slightly different orientations to each other.

a mirror

The car will tend to turn to the left. Because the left wheel hits the gravel first and slows down before the right wheel, the right wheel covers a greater distance, causing the car to turn to the left.

The direction of the rays of light is perpendicular to the line representing the wave crests.

The speed decreases.

Wavelength decreases, and frequency will stay the same.

Thinner. Light bends more entering high index of refraction materials.

refraction

The index of refraction is inversely proportional to the speed of light in a material.

The white light emerges with the colors separated, with the red light bending the least.

Raindrops act like prisms that reflect the colors of light in particular angles depending on how the individual colors are bent by the prism. Light seen at that angle forms a bow shape.

The rainbow would appear to be a complete circle, because Earth no longer obstructs our view when we are above.

glasses with one horizontally polarized and one vertically polarized lens, because one projector is horizontally polarized and the other is vertically polarized

Violet light travels slower because it is closer in frequency to the ultraviolet resonance of the atoms in the glass.

A viewer sees a single color from a single faraway drop.

speed

The minimum angle of incidence inside a medium where light is totally reflected

reflection

inverted

converging

cannot be determined

smaller

smaller

When two parallel rays of light pass through a converging lens, the rays bend towards each other. When they pass through a diverging lens, the rays move apart from each other.

The distance between the center of the lens and either focal point is the focal length. The focal point is the point where a beam of parallel light, parallel to the principal axis, converges or appears to converge.

A virtual image, unlike a real image, cannot be displayed on a screen. A virtual image is upright, whereas a real image is inverted.

A real image can only be made with a converging lens. A virtual image can be made with either a converging or diverging lens.

less than the speed outside the material

When the lamp is closer to the lens, the rays going into the lens are diverging more quickly than when the lamp is further away. Thus, after going through the lens, they aren't converging as quickly, so it takes a longer distance for them to focus.

It does not change This explains why we refer to a focal plane. All objects with the same horizontal distance to the lens will be focused by the lens on the same plane. You can see this by selecting 2nd Point and placing one of the lamps above original lamp.

No; if the lamp is very close to the lens, the rays don't converge. The two yellow X's (on either side of the lens) are called focal points. The distance between a focal point and the lens is called the focal length of the lens. If the object is closer to the lens than this distance, the lens cannot bend the rays enough for them to converge.

They are parallel When the object is at the focal point, the rays neither diverge nor converge, but are perfectly parallel. Conversely, if the object were at infinity, the rays going from the object to the lens would be parallel, and after passing through the lens, they would converge at the focal point.

decreases / increases

does not change The focal length does not depend on the lens's diameter; a greater diameter simply allows more light to be focused.

60 cm / 120 cm

180 cm

The size of the image increases as the distance from the pencil to the lens decreases.

−2.0 Notice that the image is also twice as far from the lens as the object.

120 cm Notice that, as you saw earlier for this lens, when the object is 120 cm away, the image is also 120 cm, so the ratio of the distances s and s′ is equal to one. In fact, as you might have guessed by now, the magnification can also be expressed as M=−s′s.

As a source of secondary wavelets

overlapping waves

Diffraction is more pronounced through a small opening, where small is compared to a wavelength.

AM waves, because the wavelengths are a hundred times longer than FM waves

diffraction

all types of waves

Optically flat means that surface irregularities are small compared to the wavelength of light.

Interference between light reflected from the top and bottom of an air gap when the curvature side of a convex lens rests on a flat glass

It is caused by the interference of light waves reflected from the top of the gasoline layer and the bottom where the gasoline floats on water. The dry surface is rough and interference works best with a flat-topped layer of water.

interference

refraction

interference

horizontally

We can expect the component that is parallel to the surface to reflect more, because it aligns with the surface - similar to a flat rock bouncing off the surface of water.

vertical component

No. While you were driving, the polarization angle of your glasses was aligned vertically to block horizontal glare from the road. For the glasses to block vertical glare from the rock face, the polarization angle would have to be aligned horizontally.

Polarization

The light that passes through the first Polaroid comes out completely polarized in the direction of that polarizer, so it easily passes through the analyzer with an aligned axis but not through one with an axis at right angles.

More of the reflected light is polarized horizontally.

Yes. Presenting two different views, one to each eye, mimics parallax and allows the brain to perceive three dimensions. Yes. Moving one or both eyes sideways relative to a scene allows the brain to perceive the scene in three dimensions. Yes. Moving a scene to the side relative to an observer or rotating a scene allows the brain to perceive it in three dimensions.

Polarizing filters allow the left-eye image to be seen only by the left eye, and the right-eye image to be seen only by the right eye.

The hologram appears to be three dimensional. You can look around objects in a hologram.

The amplitude decreases with distance. The amplitude of the electric field decreases with distance from the source. You can also see this by selecting Show Graph. As a result, the intensity of the light, which is proportional to the amplitude squared, also decreases with distance from the source.

The intensity is roughly constant. The light wave spreads out circularly, so the amplitude of the wave simply depends on the distance from the screen to the light source, as we saw in Part A. All locations on the screen are nearly the same distance to the source, so the amplitude is roughly constant. The intensity of the light is proportional to the amplitude squared. Therefore, since the amplitude is nearly constant, so is the intensity.

The intensity is roughly constant. Since the slit width is small compared to the wavelength, the light passing through the slit spreads out nearly circularly, so the intensity behaves similarly to when there is no barrier (although the intensity is lower).

The intensity is large near the middle of the screen, then decreases to nearly zero, and then increases again as the distance from the middle of the screen increases. Circular waves come out of each of the two slits. However, in contrast to one slit, an interference pattern occurs with two slits, due to the two spherical waves overlapping. This interference pattern has several locations with a high intensity, alternating with locations where the intensity is nearly zero. If you look carefully at the screen, you will see faint red lines, called fringes, where the intensity is relatively large.

The difference in the distances is equal to the wavelength of the wave. Since the extra distance the wave travels from one of the slits is exactly equal to the wavelength, the crests of one of the waves still meet up with the crests of the other wave, causing constructive interference. As you can confirm, for every location where the amplitude is relatively very large, the difference in the distances is equal to some integer times the wavelength, so that the two waves meet up exactly in phase.

The difference in the distances is equal to half the wavelength of the wave. With the difference in the distances equal to half the wavelength, the two waves are exactly out of phase, so a crest of one wave meets up with the trough of the other wave, causing the two waves to add up to nearly zero. This is destructive interference.

The fringes get farther apart as wavelength increases. As you found in Part C, a bright fringe occurs when the difference in the distances to the slits is equal to an integer times the wavelength. If the wavelength increases, this distance must increase, which causes the fringes to move further apart.

The fringes get closer together as the slit separation increases. For any location except the midpoint on the screen, the difference in the distances to the slits increases as the slit separation increases. Therefore, as the slit separation increases, all fringes move toward the center of the screen in order for the difference in the distances to the two slits to remain constant.

The spacing of the fringes does not change when the slit width changes. For slit widths that are small compared to the wavelength, the light wave diffracts through the slit and comes out as a circular wave. Decreasing the slit width simply blocks more light from going through the slit, but doesn't change the interference pattern.

The spacing of the fringes does not change when the amplitude changes (just the brightness changes). The interference pattern of fringes depends only on the wavelength, the slit separation, and the distance from the slits to the screen. Increasing the amplitude simply makes the fringes brighter. An equation that summarizes the results of the last several questions is Δy=λL/d, where Δy is the distance between consecutive bright fringes, λ is the wavelength, L is the distance between the slits, and d is the distance between the screen and the slits.

Yes, interference also occurs for both of these types of waves. Interference is a very common phenomenon that can occur with any type of wave.

electrons

The state has a precise energy

Highest Arrow = from outer edge to center 2nd Highest Arrow = second closest ring to the outer edge to center 3rd Highest Arrow = middle circle to center Lowest Arrow = outer edge to middle circle As your answer correctly shows, the emitted photon must have exactly the same amount of energy that the electron loses in moving from the higher to the lower energy level. Therefore the ranking of the photon energies must be in the same order as the amounts of energy lost by the electrons, and longer arrows mean greater changes in energy.

^The above but backwards^ From Part A, you already know the ranking of the photons by energy. Because higher energy means shorter wavelength, you have correctly found that the ranking for Part B is the reverse of that from Part A.

Longest arrow is highest As your answer correctly indicates, the atom in which the electron leaves (the atom is ionized) corresponds with the highest-energy photon, and the atom with the shortest arrow indicates the case where the absorbed photon had the lowest energy.

Electrons in outer shells have higher potential energy.

The energy is proportional to the frequency.

Blue light, blue light

The colors of the flames indicate the types of atoms that are emitting light in the flame.

electrons

frequency

A spectroscope displays the spectrum of light as brightness versus wavelength.

The peak frequency is proportional to the absolute temperature.

The intensity increases.

The wavelength decreases.

The total energy per unit area increases; we know this because the area under the graph increases when the temperature increases.

absorption

Fraunhofer lines are the absorption spectrum of the outer solar atmosphere viewed against the continuous spectrum of the Sun.

An emission spectrum consists of bright lines against a dark background, whereas an absorption spectrum consists of dark lines against a bright rainbow background.

Observer A detects the same wavelength and the same frequency. A propagating wave is characterized by its speed, direction, wavelength, and frequency. If the radiating source is at rest with respect to the observer, then the wave motion is uniform in all directions, with all observed wavelengths and frequencies being the same.

Observer A detects a relative stretching between wave crests, yielding a longer wavelength and lower frequency, that is, a redshift. When a radiating source is in motion relative to a particular reference frame, the wave motion is no longer uniform in all directions. According to the Doppler effect, the distance between wave crests (the wavelength) is either shortened or lengthened, depending on whether the motion between the radiating source and the observer is toward or away from one another. In the figure, approaching motions between the source and Observer B produce waves that are shortened, or blueshifted. Receding motions between the source and Observer A produce waves that are lengthened, or redshifted. It does not matter if the observer or the radiating source is in motion—it is the relative motion between the two that creates the Doppler effect. Motions of the source perpendicular (transverse) to the observer do not produce any Doppler effect.

CAB By tracking the Doppler shifts in the spectra of cosmic sources, astronomers have determined that the stars and gas clouds in our Milky Way galaxy have line-of-sight (radial) velocities that can be understood in terms of the Milky Way's rotation. Beyond the Milky Way, most other galaxies are observed to have redshifted spectra, and hence they are receding from us at hundreds of kilometers per second.

Each type of spectrum is unique in the way the wavelengths (colors) of light are distributed. The continuous spectrum shows a continuum of all the colors, whereas the emission spectra show only specific lines of emitted color. The absorption spectra show only small black ranges where specific colors have been absorbed away.

The defining differences among the diagrams result from the types of light sources and their characteristics. It is important to identify the connections between the type of spectrum and the temperature and density of its source. A continuous spectrum is produced by a hot, high-density light source. An emission spectrum is produced by a hot, low-density light source. An absorption spectrum is produced by a hot, high-density light source shining through a cool, low-density medium.

Spectroscopy is an extremely valuable method of astronomical study. Astronomers can determine the composition, density, and temperature of celestial objects by interpreting the light that is either emitted or absorbed by the objects.

The ultraviolet light photons have higher energy than visible light photons, whereas the infrared have lower energy. Thus, some of the ultraviolet energy can be reemitted as visible color.

time delay

A metastable state is a long-lived excited state.

The LED lasts 100 times longer.

Primary excitation is when electrons collide with and excite mercury gas. Secondary excitation is when ultraviolet light from the mercury excites a phosphor to emit visible light.

Air contains oxygen that would react with and destroy the tungsten filament. Argon is an inert gas.

A laser beam propagates in one direction, with one wavelength that is all in phase. Light from an incandescent lamp does none of these.

Sunlight has a wide range of frequencies, wavelengths, and phases, whereas coherent light has one wavelength, one frequency, and one phase.

Sunlight has a wide range of frequencies and wavelengths, whereas monochromatic light has one wavelength and one frequency.

absorption The solar spectrum is an absorption spectrum, with dark lines called Fraunhofer lines in honor of Joseph von Fraunhofer who discovered them.

a photon of ultraviolet light