Physics unit test
Low frequency light will not ______ to a particle - the energy must _______ (photon).
"add" energy, come in one packet
A Has Wavelengths F Can have the shape of a longitudinal wave L Sound Waves B Propagates at faster speeds in denser material G Transports Energy M Radio Waves C Propagates at slower speed in denser material H Transports Matter N Ultraviolet Waves D Oscillates Matter J Can travel through a vacuum P Ultrasonic Waves E Can have the shape of a transverse wave K Can travel through a medium like glass Q Can be blocked by crossed Polaroids
Mechanical: BFLPD Both: AEGK Electromagnetic: CJMNQ
Circle the letter of each statement that is true. a. When light is of a single color, diffraction can produce sharp diffraction fringes at the edge of the shadow. b. In white light, the fringes merge together to create a fuzzy blur at the edge of a shadow. c. The extent of diffraction does not depend on the relative size of the wavelength compared with the size of the obstruction that casts the shadow. d. When the wavelength is long compared with the obstruction, the wave diffracts less.
a and b
A beam of light consistns of...
photons
Circle the letter of the process in which sound or light is absorbed and reemitted in all directions. a. reflection b. resonance c. scattering d. stimulated emission
scattering
If you shake a rope up and down, it becomes polarized
vertically.
Electromagnetic waves are caused by...
vibrations of electrical and magnetic fields.
The energy in an electromagnetic wave is part...
magnetic and part electric
How does a secondary rainbow form?
A secondary rainbow forms when sunlight is doubly reflected within raindrops.
Circle the letter that describes what occurs when many particles larger than oxygen and nitrogen molecules are in the atmosphere. a. The sky appears darker blue. b. The sky appears black. c. The sky appears whitish. d. The sky appears green.
C
List four types of Mechanical waves, two that move as longitudinal waves and two that move as transverse waves
Longitudinal Sound waves in air, water, rock. Slinky waves when you push them away from you and then pull them towards you. The waves in your brain when you have a concussion. People standing in line for a movie when someone runs into the back of the line. Sound waves in musical instruments like flutes. P waves in an earthquake Transverse Water waves at the top surface of the ocean or pool. Slinky waves when you push them side to side. Waves on musical instrument strings. "The Wave" at a stadium. S waves in an earthquake
. Young realized that the bright fringes of light resulted from _________ and that the dark areas resulted from _________ .
Constructive interference and destructive interference
Explain why, if each drop of water disperses a full spectrum of colors, an observer can only see a single color from any one drop.
Different colors are bent different amounts. Violet light is slowed down more and bent more by water. If violet light from a single drop enters your eye, red light from the same drop falls below your eye. To see red light you have to look at a drop higher in the sky.
What did Thomas Young discover in 1801?
Discovered that light produces bright and dark fringes when passing through narrow, closely spaced slits (interference pattern), supporting the theory that light is a wave
What kind of waves are EM Waves? (Longitudinal or Transverse) How do we know?
EM Waves are transverse. We know because they cannot go through two crossed polaroids.
Explain why many areas have poor FM radio reception, but good AM reception.
FM radio waves have shorter wavelengths than AM waves do, so they don't diffract as much around buildings, and aren't received as well as AM radio waves are in mountain canyons or city "canyons."
Is the following sentence true or false? The sky appears blue because particles in the atmosphere scatter low-frequency light. T / F
False: The scatter HIGH frequency (short wavelength) light
What happens to the speed of a light wave as it goes from air to water? Why?
It slows down and bends towards the normal (unless it was coming in on the normal, in which case it does not bend at all) The light slows down because it has to be absorbed and reemitted by more particles, and this takes longer! The frequency DOES NOT CHANGE and the wavelength gets smaller
What happens to the speed of a sound wave as it goes from air to water? Why?
It speeds up and bends away from the normal (unless it was coming in on the normal, in which case it does not bend at all). The wave speeds up because the molecules are closer together and they bump into each other faster. The frequency DOES NOT CHANGE and the wavelength gets longer
What does Huygens' principle state?
Light waves spreading out from a point source may be regarded as the overlapping of tiny secondary wavelets, and every point on any wave front may be regarded as a new point source of secondary waves.
Is the following sentence true or false? If the size of an object viewed in a microscope is the same as the wavelength of light, the image of the object will be blurred by diffraction.
Light will diffract around the object and make a fuzzy image.
Although violet light is scattered more than blue light, our eyes see the sky as blue. Explain.
Our eyes are more sensitive to blue light than to violet light, so we see the sky as blue and sunlight contains more blue than violet light.
Why aren't rainbows completely round?
Rainbows are not completely round because the ground gets in the way of these dispersions of light.
Label each statement true or false: _____EM Waves all move at the same speed in a vacuum and that speed is 3 x 108 m/s _____All EM Waves can go through normal glass Ultraviolet waves do not go through normal glass _____Sound waves can go through a vacuum ____Some mechanical waves can go through a vacuum If you have to vibrate something then you cannot go through a vacuum! ____All EM Waves move as transverse waves _____Mechanical waves require a medium to travel _____Radio waves travel much faster than sound waves because Radio waves are EM Wave and Sound wave is mechanical. _____Sound waves in air travel faster than sound waves in water All Mechanical waves get FASTER as they move into denser materials. _____Visible light waves in air travel faster than visible light waves in water All EM waves get FASTER as they move into LESS dense materials. They are the opposite of Mechanical. _____All EM Waves travel at 3 x 108 m/s in every material (glass, air, water...) The 3 x 108 m/s is the speed of EM waves in a vacuum. They get slower in other materials. _____Nothing in the universe travels faster than 3 x 108 m/s.
T, F, F, F, T, T, T, F, T, F, T
Define polarization.
The aligning of vibrations in a transverse wave, usually by filtering out waves of other directions.
What happens to the frequency of ANY wave as it goes from air to water? Why?
The frequency does not change because a wave is born with that frequency (it is the energy of the wave) and it never changes (energy is conserved)
Describe what happens to light from an unpolarized source that falls on a polarizing filter.
The light that is transmitted is polarized light in the same direction as the axis of the filter; light polarized perpendicular to the filter is absorbed.
How are the photographs taken in order to be used in the 3-D slide show?
The photographs are taken a short distance apart (about average eye spacing).
What needs to happen in order for a person to see a rainbow?
The sun must be shining in one part of the sky, and the water droplets in a cloud or in falling rain must be in the opposite part of the sky.
Describe the relationship between the size of a particle in the atmosphere and the frequency of the light it scatters.
The tinier the particle, the higher the frequency of light it will scatter.
How is the viewer able to see the 3-D effect in the show?
The viewer wears polarizing eyeglasses with the lens axes also at right angles. Each eye sees a separate picture that the brain interprets as one to give a feeling of depth.
How are the photographs used in the slide show projected?
Their polarization axes are at right angles to each other. The filter used on the left projector is aligned horizontally. The filter on the right projector is aligned vertically.
What would happen if a thicker hair were used to make the interference pattern? What would happen to the interference pattern if a red laser were used? a blue laser?
Thicker hair with same laser = narrower interference pattern and Δ y is smaller Red laser = longer wavelength and interference pattern is wider or Δ y is larger Blue laser = slightly longer wavelength and interference pattern is slightly wider or Δ y is again larger
What happens when light passes through a narrow slit?
When light passes through a narrow slit, it casts a fuzzy shadow because the light is diffracted by the thin slit. The "fuzziness" is caused by a series of nodes (dark spots) and anti-nodes (bright spots) from different wavelengths that overlap.
We can identify exoplanets with two different methods. Explain both.
Transit method - where we look at the light from a star and notice a "dip" in the brightness periodically where the planet passes in front of the star. This only works if we are on-axis! Wobble / Doppler Method - where we notice the redshift and blueshift in the spectral lines of certain gasses like Sodium. This is due to the planet and the star orbiting each their center of gravity, which makes the star move away from us (redshift) and then towards us (blueshift) periodically. This does not work if the axis of the solar system is perfectly perpendicular to our line of sight.
Electromagnetic waves of frequencies slightly higher than the violet waves of visible light are called
Ultra violent
How are the axes of polarized sunglasses aligned in order to eliminate glare from horizontal surfaces?
Vertically polarized because glare (light reflected from highly reflective surface) is horizontally polarized.
Circle the letter of the color of light that is scattered the least as it passes through the atmosphere. a. red b. orange c. yellow d. blue
a
Name the different waves that make up the electromagnetic spectrum in order from a: the longest wavelength, to g: the smallest wavelength
a. radio e. ultraviolet b. microwave f. x-ray c. infrared g. gamma ray d. visible
When light refracts into a medium with a faster speed of light the _____ is larger than the _____(unless the angle of incidence is 0 degrees).
angle of refraction, angle of incidence
When light refracts into a medium with a slower speed of light the _____ is smaller than the _____ (unless the angle of incidence is 0 degrees)
angle of refraction, angle of incidence
More diffraction is seen through an _____ as the wavelength _____.
aperture, increases
As the path of sunlight through the atmosphere increases, what color of light is scattered more?
blue
Constructive interference causes the ______ in a laser diffraction pattern, and destructive interference causes the______.
bright spots, dark spots
Dispersion of light through a prism is due to...
different indexes of refraction for different wavelengths of light.
Huybens' Principle is one model for explaining
diffraction and interference patterns.
A multitude of closely spaced parallel slits make up what is called a(n)
diffraction grating.
Any bending of a wave by means other than reflection or refraction is called
diffraction.
A prism separates colors of light by ______ a diffraction grating separates colors by ______
dispersion, diffraction and interference
The number of regions of destructive interference in an interference pattern depends on the wavelength of the waves and
distance between the sources or slits
The Doppler shift applied to starlight (redshift and blueshift) provides evidence of...
exoplanets and the expansion of the Universe.
An inverse relationship exists between...
frequency and wavelength for waves that travel at the same speed.
If you shake a rope from side to side, it becomes polarized
horizontally
Electromagnetic waves of frequencies slightly lower than the red waves of visible light are called
infrared
Within an _______ wave amplitudes may be increased, decreased, or neutralized.
interference pattern
What is monochromatic light?
light of a single color or wavelength
What is the source of the energy in light
source of light = accelerating charge
he frequency of a photon is directly proportional to...
the energy of the photon.
Destructive interference is caused when...
the path difference from two wave sources is an integer multiple of the wavelength plus one half wavelength.
Cosntructive interference is caused when...
the path difference from two wave sources is an integer multiple of the wavelength.
Colors of light are related to...
the wavelength of lights