# Scientists discovered how to avoid a speeding ticket

The researchers from University of Leicester found that the drivers could escape detection by driving so fast that their number plates would appear invisible to speed cameras.

• The car would need to be travelling at about 192 million km/ hr to make the number plate invisible.
• This speed equates to one sixth of the speed of light and no man-made vehicle is capable of going anywhere near this speed.
• The fastest man-made object – the Helios Probe – is only capable of travelling at one five thousandth of the speed of light.

Mechanism to avoid a speeding ticket

• The calculations are based on the Doppler Effect – the physical effect where the frequencies of light or sound waves emanating from an object increase or decrease when it moves towards or away from us.
• With light, this process creates ‘red shift’ – where the frequency of light from an object travelling away from the observer is shifted towards the red end of the colour spectrum.
• The faster an object is travelling, the bigger the shift in frequency.
• It would theoretically be possible for the light from a fast-moving car number plate to be shifted out of the frequency range which speed cameras are able to detect.
• Assumption: The camera would be able to detect a similar frequency range as the human eye – roughly 400 terahertz at the ‘red’ end of the spectrum to 790 terahertz at the violet end.
• Generally, Car number plates are yellow ( frequency of around 515 terahertz).
• To work out the necessary speed of the car for the number plate to be ‘shifted’ past the 400 terahertz boundary of the visible spectrum, the researchers utilized the equation used by astronomers to calculate how fast stars are travelling away from the Earth.
• They found the car would need to be travelling at 53 million m/sec equal to one sixth of the speed of light.

Note: The study published in the Journal of Physics Special Topics.

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