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| howto:hambasics:sections:waveinteraction [2020/11/08 16:23] – va7fi | howto:hambasics:sections:waveinteraction [2021/01/03 08:08] (current) – va7fi |
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| * Note though that this particular animation only works if the laser is below the horizontal line. | * Note though that this particular animation only works if the laser is below the horizontal line. |
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| <WRAP centeralign> | {{ggb>/howto/hambasics/sections/snells2.ggb 705,403}} |
| {{ggb>howto/hambasics/sections/snells2.ggb 705,403}} | |
| </WRAP> | |
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| \$n_1\$ and \$n_2\$ are the [[wp>Refractive_index |Refractive Indices]] of the media. They are defined as the ratio of the speed of light in vacuum to the speed of light in the media \$\left(n = \frac{c}{v}\right)\$. For example, if \$n = 2\$, then the speed of light is twice as //slow// in the medium as it is in vacuum. The bigger \$n\$ is, the slower the speed. \$n = 1\$ means that the speed is the same as the speed of light in a vacuum. | \$n_1\$ and \$n_2\$ are the [[wp>Refractive_index |Refractive Indices]] of the media. They are defined as the ratio of the speed of light in vacuum to the speed of light in the media \$\left(n = \frac{c}{v}\right)\$. For example, if \$n = 2\$, then the speed of light is twice as //slow// in the medium as it is in vacuum. The bigger \$n\$ is, the slower the speed. \$n = 1\$ means that the speed is the same as the speed of light in a vacuum. |
| The first thing to notice is that when a wave reflects off a surface, it suffers a half-wavelength phase shift. This means that if the receiver is right next to the "mirror", the signal will cancel out. | The first thing to notice is that when a wave reflects off a surface, it suffers a half-wavelength phase shift. This means that if the receiver is right next to the "mirror", the signal will cancel out. |
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| <WRAP centeralign> | {{ggb>/howto/hambasics/sections/multipath.ggb 700,300}} |
| {{ggb>howto/hambasics/sections/multipath.ggb 700,300}} | |
| </WRAP> | |
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| If the receiver then moves away from the "mirror", the <fc #008000>reflected signal</fc> has to travel over a longer distance than the <fc #4682b4>direct signal</fc> before reaching the receiver. This means that phase between the two waves will change, sometimes cancelling each other, sometimes reinforcing each other. When the path difference (Δ) between the reflected and direct waves is a whole number of the wave length, the two waves cancel each other because of the half-wavelength difference from the reflection. But when the difference is a multiple of a half wavelength, the two waves add up constructively and the resulting signal is stronger. | If the receiver then moves away from the "mirror", the <fc #008000>reflected signal</fc> has to travel over a longer distance than the <fc #4682b4>direct signal</fc> before reaching the receiver. This means that phase between the two waves will change, sometimes cancelling each other, sometimes reinforcing each other. When the path difference (Δ) between the reflected and direct waves is a whole number of the wave length, the two waves cancel each other because of the half-wavelength difference from the reflection. But when the difference is a multiple of a half wavelength, the two waves add up constructively and the resulting signal is stronger. |
