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PAPhysicsScience Radar . I magine trying to land a jumbo jet the size of a large building on a short strip of tarmac, in the middle of a city, in the depth of the night, in thick fog. If you can't see where you're going, how can you hope to land safely?  Airplane  pilots get around this difficulty using  radar , a way of "seeing" that uses high-frequency  radio  waves. Radar was originally developed to detect enemy aircraft during World War II, but it is now widely used in everything from police speed-detector guns to weather forecasting. Let's take a closer look at how it works! Photo: This giant radar detector at Thule Air Base, Greenland is designed to detect incoming nuclear missiles. It's a key part of the US Ballistic Missile Early Warning System (BMEWS). Photo by Michael Tolzmann courtesy of  US Air Force . Contents What is radar? How does radar use radio? How does radar work? What is radar used for? Countermeasures: how can you ...

PAPhysics Science         Application of sound waves in technology          Application of sound waves in technology Parking sensor Parking sensor  systems use ultrasonic proximity detectors embedded in the front and/or rear bumpers, to measure the distances to nearby objects at low level. The sensors measure the time taken for each sound pulse to be reflected back to the receiver.Depending on the speed of the vehicle and the distance to the obstacle, the system will warn the driver by visual and/or audible means about the risk of collision. The feedback to the driver will generally indicate the direction and proximity of the obstacle. Warnings are deactivated when the vehicle exceeds a certain speed, and can be switched off for situations such as stop-and-go traffic. Radiology   Radiology  is medical specialty that employs the use of imaging to both diagnose and treat disease visualized within the...

Pitch and Frequency ·          Pitch and Frequency ·          Intensity and the Decibel Scale ·          The Speed of Sound ·          The Human Ear A sound wave, like any other wave, is introduced into a medium by a vibrating object. The vibrating object is the source of the disturbance that moves through the medium. The vibrating object that  creates the disturbance could be the vocal cords of a person, the vibrating string and sound board of a guitar or violin, the vibrating tines of a tuning fork, or the vibrating diaphragm of a radio speaker. Regardless of what vibrating object is creating the sound wave, the particles of the medium through which the sound moves is vibrating in a back and forth motion at a given  frequency . The  frequency of a wave  refers to how often the particles of the me...