Speed gun

24.12.2024

Speed gun

Why in the news?     

              Speed guns are widely used by law enforcement officials to monitor traffic speed and in various other industries.

About Speed gun:

• It is a device to measure the speed of a moving object without having to be in contact with the object.
• To achieve this, the device bounces electromagnetic radiation of a specific frequency off the object, capturing the reflection and using the Doppler effect to infer the object’s speed.
• Speed guns are electronic, and use complex circuitry to emit the radiation used to make the measurement.
• The speed gun was originally developed during World War II for military use and applies the effect using radio waves rather than sound waves.

How does it work?

• A speed gun has a radio transmitter and a receiver.
• The transmitter emits radio waves, which the person holding the speed gun can direct at an object. The receiver collects the waves reflected by the object back in the direction of the speed gun.
• If the object is approaching the speed gun, the frequency of the returning waves will be slightly higher than that of the transmitted waves. A simple computer in the gun can deduce the object’s speed based on this difference.

How are the speed and the effect linked?

○All electromagnetic waves have a fixed speed — equal to the speed of light in that medium.

○In vacuum, this value is denoted c: 299,792,458 m/s. Any change in the frequency the speed gun detects directly corresponds to the Doppler shift caused by the object’s motion.

○This principle is powerful because it allows the speed gun to work accurately over a wide range of distances and velocities without being affected by air resistance.

○A speed gun can calculate the speed of a moving object by multiplying the difference (between received and emitted frequencies) with c and dividing by the emitted frequency times 2.

○This relationship shows how the difference is directly proportional to the speed of the object: the faster it moves, the more pronounced the difference will be.

• Uses: It is widely used by law enforcement officials to monitor traffic speed, by coaches to gauge the performance of their athletes, and in various other industries in need of accurate motion tracking.

                                                                          Source: The Hindu

With reference to the Speed gun, consider the following statements:

1. It is a device to measure the speed of a moving object without being in contact with the object.

2. It uses the Doppler Effect to infer the object’s speed.

3. It is used to monitor the speed of the traffic.

How many of the above statements are correct?

A.Only one

B.Only two

C.All three

D.None

Answer C