Physical Science Ch.7 Questions online

particle model of light.

Light can produce a current through the photoelectric effect. Light travels in straight lines. The energy of light depends on its frequency, not its intensity.

The current understanding of light is best summarized by ?

Light exhibits characteristics of waves and particles, and either model may be appropriate for a given situation. Rationale: Scientists use the model most appropriate to the situation.

The result of shining a light on a particular material is that the material absorbs the light and emits electrons. This is known as the __________ effect.

Photoelectric effect

The smallest single quantum (or packet) of energy produced by a source emitting blue light would be a blue ____________.

Photon

This is the photoelectric effect.

Photon model

Total internal reflection of a light ray means that ______.

the light ray does not escape the material the angle of refraction is at least 90°

The higher the index of refraction of a material, ______ when entering the material (at any angle except perpendicular).

the more light will bend Rationale: A larger value of n means more refraction.

Can form an enlarged virtual image

Concave B

Light can pass through empty space.

Electromagnetic wave model.

It determines what color an object appears.

Absorption

The result of light hitting a rough surface

Diffuse Reflection

Highest frequency; medical treatments

Gamma rays

Lowest frequency; cellular phones, broadcast television, cooking

Microwaves

A concave mirror ______.

-Is bowl-shaped, with the inside lower than the edges -of the right curvature will create a magnified virtual image -of the right curvature will create a real image

The amount of refraction that occurs as light passes between two media depends on ______.

-the ratio of the index of refraction of the materials -the ratio of the speed of light in the materials -the angle of incidence on the boundary

Global Positioning System.

24 satellites Atomic clocks Time-encoded radio signals

Driving on the highway at night, you turn on your car's headlights. If you could measure it, the light emitted by the headlights would travel away from the car at (approximately) 3.00 × 108 m/s. If a person standing ahead of your car on the highway measured the speed, it would be ______.

3.00 × 108 m/s

A hot object (such as an electric burner) starts to glow red when the temperature reaches ______. An incandescent lightbulb (tungsten filament) glows yellow-white at a temperature of about ______.

700°C (1,300° F) 2,200°C (4,000°F)

It determines what fraction of light is transmitted through a clear object.

Angle of the ray

all the places where light of the same wavelength from two sources would interfere constructively.

At a location where the troughs of both waves arrive at the same time At a location where light from one source travels exactly two wavelengths farther than light from the other At a location where the peaks of the two waves arrive simultaneously

______ is the term for the information-carrying capacity of a transmission medium, such as a fiber optics cable.

Bandwidth

Light travels more slowly in water than air. When it emerges from the water, the light ray will ______.

Bend to position D, away from the normal

laser light.

Coherent In phase (waves are aligned) Single frequency

This is the addition of two aligned waves, resulting in a region brighter than either wave alone.

Constructive interference

Can form a virtual image with a wide field of view

Convex A

This is the cancellation of two waves that are misaligned, resulting in a region dimmer than either wave alone.

Destructive interference

It explains why shadows are not absolutely black.

Diffuse reflection

In the production of light by an incandescent source, internal heat moves particles that make up the glowing object. The moving nuclei and electrons ______.

Disturb the electric and magnetic fields in the material, creating electromagnetic radiation. -Accelerating charged particles create electromagnetic waves. The hotter the object, the more acceleration occurs, and the more light is produced.

He explained the photoelectric effect in terms of photons.

Einstein

Explain the generation of light at a source.

Electromagnetic wave model

He showed that light traveled more slowly in transparent materials than in air.

Foucault

The property that determines the energy of individual photons

Frequency

Demonstrated that many of light's properties can be represented mathematically as waves and measured the wavelengths of visible colors of light.

Fresnel

Relates gravity and the structure of space and time

General theory of relativity

Proposed that light was a longitudinal wave.

Hyugens

Filament light bulbs, the wires in a toaster, and a fire are all examples of ___________ light sources, which produce light over a wide range of wavelengths.

Incadescent

As Θi increases, the angle of reflection (Θr) measured from the normal ______.

Increases

Lowest frequency; cellular phones, broadcast television, cooking

Infrared light

The number of photons emitted by a light source

Intensity

This describes a series of bright and dark spots or stripes resulting from the interaction of waves.

Interference pattern

If you were designing a microscope or telescope, the ______________________ model would be helpful for tracing light's path through the device.

Light ray

Select the statements that accurately summarize our present understanding of light.

Light sometimes acts as a wave and sometimes as a particle. The energy of light is divided into discrete packets called photons. The exact nature of light is not describable in terms of the everyday-sized world but can be approximated in different situations.

The statements below apply to real or virtual images.

Light travels directly from the image to your eye. The image can be projected on a screen or recorded.

He created electric and magnetic field theory that described light as waves of electric and magnetic fields.

Maxwell

Proposed that light was tiny particles that travel at great speed.

Newton

Einstein's special theory of relativity.

Observers perceive moving objects to be shorter in length in the direction of motion than when at rest. All observers measure the same speed for light traveling in a vacuum.

An object that reflects and/or absorbs all the light that hits it

Opaque

Explain light as individual packets of energy.

Particle Model

Light travels in straight lines.

Particle model

two principles from which Einstein developed his special theory of relativity.

Physical laws are the same in reference frames moving at constant velocity to each other. The speed of light is measured to be the same for all observers.

He determined that the energy of light depends on frequency and only exists in discrete amounts.

Planck

A conversion to relate the frequency of light to the amount of energy in a photon

Planck's constant

A tiny, finite, discrete amount

Quantum

Happens when light bounces off a smooth surface

Reflection

Depending on the angle of incidence, outgoing waves are aligned more or less horizontally with a surface.

Reflection..

The change in direction of a light ray when it passes from one substance into another (e.g., from water into air) is called _________.

Refraction.

Predict the angle of a reflection off a mirror.

Representing Lights as a Ray

Small particles absorb and reradiate light polarized with their directions of vibration.

Scattering

Only the waves aligned with the preferred polarization of the material are able to pass; others are blocked.

Selective absorption

It determines what kind of reflection occurs.

Smoothness

related to dispersing a spectrum.

Spatial separation of white light into its component colors Refraction of light A medium with an index of refraction that varies with wavelength

Explains how space and time are affected by motion

Special theory of relativity

At what time of day would you expect the most glare off a lake next to the highway?

Sunrise

The sky appears blue because short wavelengths of light are scattered more strongly by the atmosphere than long wavelengths. Select all the observations that are also a result of this scattering.

The Sun is reddest at sunset. It is still light out for a while after the Sun is below the horizon. Fluorescent objects, which respond to ultraviolet light, appear to glow the most strongly at twilight.

Low- and high-intensity light of the same wavelength is shone on the plate in the diagram. What results do you expect?

The low-intensity light produces a lower current (fewer electrons) but the same voltage (same energy).

effects of the special theory of relativity for objects moving quickly

Time passes more slowly for a moving object. An object has more mass when moving quickly than if it is at rest.

An object that transmits light

Transparent

Light exhibits polarization.

Transverse wave model

True or false: All objects with heat produce blackbody radiation.

True

true statements about observers and reference frames.

Two objects that are moving at the same velocity compared to an observer could be in the same reference frame. An observer sees her own reference frame as stationary.

Curved mirrors such as the small convex one shown in the side mirror of this automobile produce a ______ image.

Virtual

Light shows diffraction and interference patterns.

Wave model

Second highest frequency; dental and medical imaging

X-rays

Showed through experiment that light had wave properties such as interference.

Young

White light is best described as ______.

a mixture of many colors

Fiber optics cables have higher bandwidth than, for example, a radio transmission, because ______.

a single cable can carry many different frequencies of light at the same time

The light produced by incandescent light sources is generated by ______.

accelerating electric charges

The speed of light in a vacuum is approximately 3.00 × 108 m/s. Light traveling through a material (such as air, or glass, or water) ______.

always travels at a reduced velocity

The information-carrying capacity of a transmission medium, such as a fiber optics cable, is its ______

bandwidth

When light moves from a material with a higher speed of light into a material with a lower speed of light, the light ray ______.

bends toward the normal

Plants and animals that produce their own light are said to be ______.

bioluminous

This image shows the path of light in the eye of a person who is nearsighted. The light can be made to focus on the retina by using a ______ to ______ the light rays before they enter the eye.

concave lens; diverge Rationale: The diverging lens spreads the rays out so they take a longer distance to focus.

This image shows the path of light in the eye of a person who is farsighted. The light can be made to focus on the retina by using a ______ to ______ the light rays before they enter the eye.

convex lens; converge

Visible light is only part of the entire ____________ spectrum, which is shown in the figure.

electromagnetic

A galaxy is moving away from our home galaxy of the Milky Way at 25 percent the speed of light. If an astronomer measured the speed of light emitted by that galaxy, it would be ______.

equal to 3.00 × 108 m/s

Considering the formula for the energy of photons, an ultraviolet photon with a wavelength of 250 nm would have an energy ______ that of an infrared photon with wavelength 1,000 nm.

four times higher than

The higher the ______ of a light source, the higher the energy of each individual photon emitted.

frequency

We must model light as a wave or a particle depending on the situation because ______.

light is a small-scale phenomenon, and nature behaves differently on tiny scales

A mirage of a lake in the desert or of a car's reflection on a hot road happens because ______. (Hint: The index of refraction of cold air is slightly more than that for hot air.)

light rays in hot air traveling parallel or toward the ground are bent upward at you when they encounter colder air higher up

In Einstein's theory of general relativity, gravity is described by considering how ______ affect(s) ______.

masses the structure of spacetime

A radioactive particle moving at close to the speed of light takes longer to decay than a stationary sample in a lab. This is an example of the effect that ______ in the special theory of relativity.

moving clocks run more slowly

One reason that it is difficult to understand the dual wave-particle nature of light is that ______.

our experience with the everyday world is limited to phenomena that behave strictly as one or the other

Normally, a light wave oscillates in various directions perpendicular to its direction of motion. However, certain filters only transmit light oscillating in one particular direction. Such light is ______.

polarized

To measure the velocity of a car, you must find how fast it is moving compared to something else—for example, the road. In this example, the road defines a ______.

reference frame

A rainbow is made of arcs of color rather than straight lines because ______.

the arc of a given color defines a constant angle between you, the raindrops, and the Sun

Einstein's special theory of relativity is based on two principles. One is that the speed of light (in empty space) has the same value for all observers. The other is that ______.

the laws of physics are the same in frames that are moving at constant velocity to each other

Sometimes two rainbows are visible, one outside the other. The colors of the outer rainbow are reversed because ______.

the light making up the second rainbow was reflected twice inside raindrops

The speed of light is equal to ______. (In fact, the speed of any wave is equal to this combination.)

the product of wavelength times frequency (λ × f)

Dispersion of light means ______.

the separation of light into different colors sorted by wavelength

In the double-slit experiment, dark stripes appear on the screen at the locations where the distance from the location ______.

to one slit is a whole number of wavelengths, and to the other, a whole plus 1/2 a wavelength

If a photon of green light has a frequency of 6.0 × 1014 Hz and a photon of red light has a frequency of 4.0 × 1014 Hz, then the energy of the red photon must be ______.

two-thirds as much as the energy of the green photon

The index of refraction of water is 1.33, and the index of refraction of glass is about 1.50. This means that light travels more quickly in ______.

water

the speed of light (or indeed any wave) is equal to the product of the wave's ______ and ______.

wavelength and frequency

Refraction of a light ray occurs ______.

when a light ray changes direction passing through the boundary between two materials