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marellasunny
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Say I have a radar transmitter on a car,used to detect its distance from a car in front of it by measuring the doppler shift on the reflected wave.
i.e Car 1 is the source, its wave gets reflected by Car 2 in front of it.
My book splits the problem of calculating the Doppler shift by computing the frequencies w.r.t relative velocity.
1.When the source emits(Car1),take it as stationary by considering the receiver to move at relative velocity.
2.When the receiver reflects(Car2),take it as stationary by considering the source to move at relative velocity.
The book goes on to give the following statements:
1.If the sender moves relative to a static receiver,the wavelength changes.The received frequency now will be:
$$f_{receiver}=\frac{c_{sent}}{\lambda_{receiver}}=\frac{{c_{sent}}}{\lambda-\frac{v_{rel}}{f}}$$
2.If the receiver moves relative to a static sender,the propagation velocity changes**(but not the wavelength??)**.The received frequency now will be:
$$f_{receiver}=\frac{c_{receiver}}{\lambda}=\frac{c_{sent}+v_{relative}}{\lambda}$$Q***Shouldn't the wavelength also change when the waves get reflected back by the moving receiver?*** The above equation no.2 says it doesn't.
I can't attach images because I just joined.
i.e Car 1 is the source, its wave gets reflected by Car 2 in front of it.
My book splits the problem of calculating the Doppler shift by computing the frequencies w.r.t relative velocity.
1.When the source emits(Car1),take it as stationary by considering the receiver to move at relative velocity.
2.When the receiver reflects(Car2),take it as stationary by considering the source to move at relative velocity.
The book goes on to give the following statements:
1.If the sender moves relative to a static receiver,the wavelength changes.The received frequency now will be:
$$f_{receiver}=\frac{c_{sent}}{\lambda_{receiver}}=\frac{{c_{sent}}}{\lambda-\frac{v_{rel}}{f}}$$
2.If the receiver moves relative to a static sender,the propagation velocity changes**(but not the wavelength??)**.The received frequency now will be:
$$f_{receiver}=\frac{c_{receiver}}{\lambda}=\frac{c_{sent}+v_{relative}}{\lambda}$$Q***Shouldn't the wavelength also change when the waves get reflected back by the moving receiver?*** The above equation no.2 says it doesn't.
I can't attach images because I just joined.
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