Understanding the Working Principle of Speed Guns
(Source – The Hindu, International Edition – Page No. – 11)
| Topic: GS3 – Science and Technology |
| Context |
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What is a Speed Gun?
- A speed gun is a device that measures the speed of a moving object without physical contact.
- It uses electromagnetic radiation, typically radio waves, which bounce off the object to calculate its speed using the Doppler effect.
- Speed guns are commonly used by law enforcement, sports coaches, and various industries to track motion accurately.
The Doppler Effect
- The Doppler effect, discovered by Christian Doppler, describes the change in frequency of waves due to the relative motion between the source and the observer.
- As a moving object approaches, the frequency of waves (like sound or light) increases, creating a higher pitch; as it moves away, the frequency decreases, resulting in a lower pitch.
- This effect is used in speed guns to calculate the speed of moving objects based on the shift in frequency of the waves.
How Speed Guns Work
- Speed guns emit radio waves, which are reflected by the moving object.
- The frequency difference between the emitted and reflected waves is used to determine the speed of the object.
- The speed is calculated using the formula: (frequency difference * speed of light) / (2 * emitted frequency).
- The speed of light in a medium is constant, allowing for accurate speed measurement over long distances.
Limitations of Speed Guns
- Radio waves emitted by the gun diverge as they travel, potentially causing inaccurate readings if multiple objects are within the radar’s beam.
- Continuous-wave radar can result in errors due to reflections from multiple vehicles.
- LIDAR speed guns, which use laser light instead of radio waves, offer improved accuracy with minimal beam divergence, overcoming these limitations.
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