Microwave how does it work physics

This radar altimeter beams microwaves at two different frequencies Combining data from other instruments that calculate the spacecraft's precise altitude and correct for the effect of water vapor on the pulse can determine the sea surface height within just a few centimeters!

Passive remote sensing refers to the sensing of electromagnetic waves that did not originate from the satellite or instrument itself. The sensor is merely a passive observer collecting electromagnetic radiation.

Passive remote sensing instruments onboard satellites have revolutionized weather forecasting by providing a global view of weather patterns and surface temperatures. In , using long, L-band microwaves, Arno Penzias and Robert Wilson, scientists at Bell Labs, made an incredible discovery quite by accident: they detected background noise using a special low-noise antenna. The strange thing about the noise was that it was coming from every direction and did not seem to vary in intensity much at all.

If this static were from something on our planet, such as radio transmissions from a nearby airport control tower, it would come only from one direction, not everywhere. The Bell Lab scientists soon realized that they had serendipitously discovered the cosmic microwave background radiation.

This radiation, which fills the entire universe, is a clue to its beginning, known as the Big Bang. This light, emitted Top of Page Next: Infrared Waves. Retrieved [insert date - e. Science Mission Directorate.

National Aeronautics and Space Administration. This Doppler-radar image seen on TV weather news uses microwaves for local weather forecasting. Shown here is Hurricane Claudette's eye-wall making landfall. For food to be heated in a microwave oven, microwaves must pass through the food. Microwaves are electromagnetic waves with a frequency of about 2. In a microwave oven, microwaves are produced by a device called a magnetron. This device takes the form of a hollow tube, with a cylindircal cathode running through the centre and the outside of the tube, shaped with several cavities, acting as an anode Gallawa Thus, an electric field exists in the gap inside the tube.

This structure is shown in Figure 1. A permanent magnetic field exists perpendicular to the electric field and parallel to the length of the tube. Electrons in the cathode are stripped into the electric field due to thermionic emission high temperature in the cathode causing the electrons to be excited and released Nave They accelerate towards the anode, the outside of the tube, due to the force applied on them by the electric field.

However, on their way, the magnetic field also applied a force to them which curves their motion. The resulting paths some electrons might take are shown in Figure 1. Because of their curved motion, the electrons are pushed towards an area where there is excess negative charge in the anode one side of a cavity.

This excess negative charge is pushed back around the cavity, creating an oscillation of electric and magnetic fields due to a moving charge Nave The frequency at which this resonation occurs is consistent with that of microwaves; since electric and magnetic fields are emitted perpendicularly to each other and perpendicular to the direction of travel at this frequency, microwaves are effectively emitted.

This process is illustrated in Figure 2. The microwaves produced by the magnetron are directed towards a spinning propellor made of metal.

The oven chamber is lined with metal so that the microwaves will continue to bounce around in the chamber until they are absorbed Heckert Originally published by Cosmos as Hot stuff: the physics of microwave ovens. Cosmos is published by The Royal Institution of Australia, a charity dedicated to connecting people with the world of science.

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Cosmos » Technology » Hot stuff: the physics of microwave ovens Share Tweet. Jake Port Jake Port contributes to the Cosmos explainer series. More from:. Jake Port.