There are many different sensors that can be used to detect motion in a given environment. Passive InfraRed (PIR) sensors are the most used today, as they work by detecting moving heat signatures.

We know the Doppler Effect as the reason why horns and sirens drop in tone as they rush by us. But the Doppler Effect works on objects that are twisting around, too. We’ll tell you how the Doppler ...

CORVALLIS, Ore. – Whether they know it or not, anyone who's ever gotten a speeding ticket after zooming by a radar gun has experienced the Doppler effect – a measurable shift in the frequency of ...

Sitting on the beach at Gecko Island one afternoon, A man finds himself beneath the flight path of the airplanes leaving East Blue Airport. a) What frequency will the man hear as a jet, whose engines ...

Everyone has experienced the Doppler effect. An ambulance’s siren has a higher pitch as it approaches you, and a lower pitch when moving away. Now, imagine that the pitch goes down as the ambulance ...

The Doppler effect, discovered in 1842 by Christian Doppler, is familiar to most of us; stationary observers of waves such as sound waves will see wavelengths that depend on the relative motion ...

Forbes contributors publish independent expert analyses and insights. I cover the history of science and exploration. Today's Google Doodle celebrates the 214th birthday of Christian Doppler, whose ...

A rotation in light's electric-field vector can alter the light's frequency. This rotational equivalent of the Doppler effect has proved surprisingly elusive, but has now been spotted in the ...

Krzysztof Bolejko receives funding from The University of Sydney. He is affiliated with Sydney Institute for Astronomy. There are so many galaxies in the universe that if you point a telescope in any ...

For the first time, scientists have experimentally shown a different version of the Doppler effect at a much, much smaller level -- the rotation of an individual molecule. Prior to this such an effect ...