Concepts:
Describe the first experiment that showed that light was a wave and how it was determined to be so.
The first experiment that showed light was a wave was Young's double slit experiment. It consisted of sunlight entering a room through a pinhole in a window shutter with a mirror that was used to direct the pinhole beam across the room horizontally. A small paper card was then used to break the pinhole beam into two different beams. Light waves from these two beams would interfere and the interference pattern was projected onto a screen where the measurements could be made and the wavelength of the light could be calculated. Light was determined to be a wave because of the interference between the two beams of light. If light wasn't a wave they wouldn't interfere.
Describe the first experiment that showed that light was a wave and how it was determined to be so.
The first experiment that showed light was a wave was Young's double slit experiment. It consisted of sunlight entering a room through a pinhole in a window shutter with a mirror that was used to direct the pinhole beam across the room horizontally. A small paper card was then used to break the pinhole beam into two different beams. Light waves from these two beams would interfere and the interference pattern was projected onto a screen where the measurements could be made and the wavelength of the light could be calculated. Light was determined to be a wave because of the interference between the two beams of light. If light wasn't a wave they wouldn't interfere.
What does it mean for two waves to be out of phase? Draw a picture of what this looks like. Do the same for waves that are in phase.
For two waves to be out of phase, they undergo destructive interference. The crests and the troughs of each part of the wave do not line up. This creates an effect on the overall wave. A lot of it, especially if the waves are 180 degrees out of phase, will cancel with the other wave. Waves that are in phase, undergo constructive interference. These waves are lined up by each crest and trough. For waves that are in phase, the amplitude of the wave increases when they come together.
For two waves to be out of phase, they undergo destructive interference. The crests and the troughs of each part of the wave do not line up. This creates an effect on the overall wave. A lot of it, especially if the waves are 180 degrees out of phase, will cancel with the other wave. Waves that are in phase, undergo constructive interference. These waves are lined up by each crest and trough. For waves that are in phase, the amplitude of the wave increases when they come together.
What do you see when light shines on a screen after passing through two closely spaced slits? Describe this phenomenon.
When light shines on a screen after passing through two closely spaced slits, you see interference fringes. This happens because the waves of light coming from these two slits will interfere with each other. Destructive interference will happen when the waves are out of phase resulting in a dimmer fringe. Constructive interference will happen when the two waves are in phase resulting in a bright fringe.
When light shines on a screen after passing through two closely spaced slits, you see interference fringes. This happens because the waves of light coming from these two slits will interfere with each other. Destructive interference will happen when the waves are out of phase resulting in a dimmer fringe. Constructive interference will happen when the two waves are in phase resulting in a bright fringe.
What do you see when light shines on a screen after passing through one narrow slit (or around one narrow barrier)? Describe this phenomenon.
When light passes through a narrow slit, it spreads out behind the slit and exhibits diffraction. The pattern on the screen will be wider if the slit is narrower or if light with longer wavelength is used. Here, interference also takes place between waves that are diffracted by the slit creating bright and dim spots where constructive and destructive interference occurs.
When light passes through a narrow slit, it spreads out behind the slit and exhibits diffraction. The pattern on the screen will be wider if the slit is narrower or if light with longer wavelength is used. Here, interference also takes place between waves that are diffracted by the slit creating bright and dim spots where constructive and destructive interference occurs.
Problems:
Two loudspeakers are 1.8 m apart. They play tones of equal frequency. If you stand 3 m in front of the speakers, exactly between them, you hear a maximum intensity. If you stay the same distance way but instead are directly in front of one of them, you hear no sound at all.
a.) What is the frequency of the sound being played?
Two loudspeakers are 1.8 m apart. They play tones of equal frequency. If you stand 3 m in front of the speakers, exactly between them, you hear a maximum intensity. If you stay the same distance way but instead are directly in front of one of them, you hear no sound at all.
a.) What is the frequency of the sound being played?
b.) Sketch the diagram that shows the maximum and the minimum.
The figure shows light passing through two narrow closely spaced slits. The graph shows the intensity of the pattern on a screen behind the slits. Use the blank axes as a guide to draw the intensity pattern if the right slit is covered (so light only goes through the left slit) and explain your reasoning.
Interference will still occur but will act like a single slit experiment where the middle will have the most intensity of light (directly in front of the left slit).
Interference will still occur but will act like a single slit experiment where the middle will have the most intensity of light (directly in front of the left slit).
A screen is placed behind two narrow slits that are separated by The figure below shoes the light intensity on the screen. What is the wavelength of the light used to form this pattern?
A diffraction grating is placed from a viewing screen. Light from a hydrogen lamp shines through the grating and a spectral line is seen to one side of center. If instead a mercury lamp is used, where will its classic spectral line appear?