Can the Doppler Effect Cause Changes in Radio Wave Frequency?

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Discussion Overview

The discussion revolves around the Doppler effect and its impact on the frequency of radio waves, particularly in the context of a car radio receiving signals from a stationary radio station while the car is in motion. Participants explore the relationship between the speed of the car, the frequency of the radio waves, and the perceived changes in frequency.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant notes that the Doppler effect causes a change in wavelength and frequency for all types of waves, questioning why they can still hear the radio at the original frequency despite their changing position relative to the station.
  • Another participant explains that while the radio is tuned to 90 kHz, it can also receive slightly shifted frequencies (e.g., 90000.009 Hz when approaching and 89999.991 Hz when moving away) due to the Doppler effect, emphasizing the small relative speed compared to the speed of light.
  • A participant seeks clarification on whether the small change in frequency is due to their speed being negligible compared to the speed of radio waves and questions the significance of energy loss.
  • Responses confirm that the frequency shift (0.009 Hz) is minor and question the notion of energy loss in this context.

Areas of Agreement / Disagreement

Participants generally agree on the minor nature of the frequency shift caused by the Doppler effect in this scenario, but there is some uncertainty regarding the concept of energy loss associated with this shift.

Contextual Notes

The discussion does not resolve the implications of energy loss in relation to the Doppler effect, and assumptions about the context of energy changes remain unaddressed.

shihab-kol
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I have learned that the Doppler effect causes a change in wavelength (and thus frequency) in all types of waves
Suppose there is a radio station transmitting waves of frequency 90 kHz and the antennae in my car is tuned to that frequency.
Then I start to accelerate and thus I am changing my position relative to the station .
Then due to Doppler effect the waves would have to travel a longer distance and thus there has to be a change in frequency of the waves due to energy loss.
But I can still hear the radio at that frequency , why does this happen?
 
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[edit] Hello shihab, :welcome: !

This happens because your radio may be tuned to 90 kHz exactly , but it also perfectly receives the 90000.009 HZ the antenna picks up when you are driving towards the sender at 108 km/h, or the 89999.991 Hz when you drive away from it.

In short: because your speed / wave propagation speed is so small (like 30/300000000 in this example)
 
So you mean to say that
BvU said:
[edit] Hello shihab, :welcome: !

This happens because your radio may be tuned to 90 kHz exactly , but it also perfectly receives the 90000.009 HZ the antenna picks up when you are driving towards the sender at 108 km/h, or the 89999.991 Hz when you drive away from it.

In short: because your speed / wave propagation speed is so small (like 30/300000000 in this example)
So, you mean to say that as my speed or velocity is very small compared to that of the radio waves that is why the frequency does not change by a huge amount ?
Is the loss in energy small?
Thanks
 
shihab-kol said:
So, you mean to say that as my speed or velocity is very small compared to that of the radio waves that is why the frequency does not change by a huge amount ?
Correct. 0.009 Hz really is a very small amount :smile: of shift for a radio wave.
shihab-kol said:
Is the loss in energy small?
What loss in energy ?
 
BvU said:
Correct. 0.009 Hz really is a very small amount :smile: of shift for a radio wave.
What loss in energy ?
Okay, I now understand .
Thank You.:smile:
 

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