end of section review questions 16

how does your eye focus light on the retina

A light ray is first refracted as it passes into the cornea of the eye. From there it passes through the pupil and then on to the lens. The lens refracts the light further so that light is focused on the retina, forming a real image.

explain how a simple magnifying glass works

A magnifying lens refracts light rays from an object near the lens so that the light from points on the object appear to be coming from points that are further apart. This produces an enlarged virtual image.

how does a flat mirror form a virtual image?

Light that reaches your eyes from the mirror comes from in front of the mirror. However, because the path of the rays goes through the mirror, you see an image that appears to be behind the mirror.

describe the law of reflection in your own words

The law of reflection states that the angle of the reflected light ray is equal to the angle of the incoming light ray.

explain why a plant may look green in sunlight but black under red light

a green leaf reflects green light. lights from the sun contains all colors, so the leaf looks green. red light contains no green, so the leaf reflects no light and appears black

describe how a mirage is formed

a mirage is formed when light bends as it passes through air with different temperatures and forms a virtual image

A spoon partially immersed in a glass of water may appear to be bent. Is the image of the spoon in the water a real image or a virtual image?

a virtual image

determine which band of the electromagnetic spectrum has the following a. the lowest frequency b. the shortest wavelength c. the most energy d. the least energy

a. radio waves b. gamma rays c. gamma rays d. radio waves

list 3 examples of the diffuse reflection of light

bike reflectors, clothing, paper

Discuss how reflection from objects that appear blue from objects that appears yellow.

blue objects reflect blue light and absorb colors in the rest of the visible spectrum. yellow objects reflect yellow light and absorb other colors

name the regions of the electromagnetic spectrum from the shortest wavelengths to the longest

gamma, x, ultraviolet,visible (from violet to red), infrared, microwaves, and radio waves

explain why sound travels slower in air than in water

in water, molecules are packed closer together; in air the molecules are farther apart and collide less often

distinguish between infra sound and ultrasound

infra sound refers to sounds that are below the range of human hearing (lower than 20 Hz). ultrasound is above the human range of hearing (above 20 000 Hz)

state one piece of evidence that supports the wave model of light and one piece of evidence that supports the particle model of light

interference, reflection, and refraction support the wave model. the fact that blue light can knock electrons off a metal plate while red light cannot (the photoelectric effect) supports the particle model

If light traveled at the same speed in glass as it does in air, could rainbows exist? explain

no, rainbows are a result of the dispersion of colors, which is caused by refraction. refraction results from the change in the speed of light as it passes from one medium to another. if light traveled the same speed in water as in air, no refraction would occur

determine which photons have more energy, those associated with microwaves or those associated with visible light

photons of visible light have higher energy because their frequency is greater

identify the two factors that affect the speed of sound

state of matter, nature of the meduim, temp.

why does an acoustic guitar generally louder than an electric guitar without an electronic amplifier sounds?

the acoustic guitar is constructed so that the hollow body vibrates in resonance with the string. electric guitars usually have a solid body that vibrates very little

a certain molecule can absorb the energy of red light but cannot absorb the energy of green light. does the wave model or the particle model of light better explain this statement? explain

the particle model of light explains this better because only certain packets of energies are absorbed

your friend tells you that a clap of thunder has a sound intensity of about 130 dB, so it is almost twice as loud as a vacuum cleaner. explain whether or not they are correct

the sound from a vacuum has an intensity of about 70 dB, so friend is incorrect. a sound that has an intensity of 130 dB is 60 dB more intense than the vacuum. a difference in 10 dB means the sound is twice as loud, so the thunder seems about 64 times as loud

explain why light is dispersed by a prism

the speed at which light travels through a prism depends on the wavelength of the light. light traveling at different speeds is bent at different angles, so the wavelengths are spread out when they exit a prism

on a piano keyboard, the C5 key has a frequency that is twice the frequency of the middle C key. is the string that vibrates to make the sound waves for the C5 key shorter or longer than the middle C key. explain

the string of the C5 will be shorter because a shorter string will vibrate faster and will have a higher frequency and a higher pitch

you and a friend are looking at the stars, and you notice two stars close together, one bright and one fairly dim. your friend comments that the bright star emits much more light than the dimmer star. is your friend correct? explain

they may be wrong because there is no way to judge. the star that appears brighter may be much closer than the dimmer star and emit less light

to create sonograms, why are ultrasound waves used instead of audible sound waves?

ultrasound vibrations travel easily through tissue, bu audible waves do not

You and a friend decide to go hiking on a cloudy day. Your friend claims that she does not need any sunscreen because the sun is not shining.What is wrong with her reasoning?

ultraviolet light from the sun has enough energy to make it through clouds, so it could still cause a sunburn

determine which two properties of a sound wave change when a sound gets louder

when a sound gets louder, the amplitude and intensity of the sound wave increase

determine which two properties of a sound wave change when pitch gets higher

when pitch gets higher, the frequency increases and the wavelength decreases

You hear a phone ring. Describe the process that occurs in your ear that results in sound waves from the phone being translated into nerve impulses that are sent to the brain.

when the phone rings, the sound travels to the outer ear and makes the eardrum vibrate. the vibrations cause the hammer, anvil, and stirrup bones in the middle ear to vibrate. the vibrating stirrup bone strikes the membrane at the opening of the inner ear and sends vibrations through the cochlea. in the cochlea, parts of the basilar membrane vibrate in response to the frequencies made by the phone. this stimulates nearby hair cells, which sends a signal to my brain. my brain interprets the frequency and intensity of the sound, and you recognize that the phone is ringing

in the dispersed light that exits a glass prism, green light is closer to violet light than yellow is. does green light or yellow light travel faster through the glass prism?

yellow travels faster than green. violet light travels the slowest through a prism, so if yellow light is farther away from violet, it must travel faster than green light

a friend says that only mirrors and other shiny surfaces reflect light. explain what is wrong with this reasoning

you see all objects by light reflected from them. therefore, anything you can see, except for direct sources of light, reflects light