Microwave

Microwave

1. short wavelenghts

   • between 1mm and 30cm

2. less expensive to run than conventional ovens.

3. microwaves penetrate about 1cm into the outer layers of food before being absorbed.

4. The energy transferred by the microwaves makes water or fat molecules in the outer layers of food vibrate more

5. Energy is then transferred from the vibrating water or fat molecules to the centre of the food by conduction.

6. Radar

   • Radar was developd during the Second World War to detect aircraft outside the normal range of sight and hearing
   • Radadr us microwavs, which pass through the atmosphere even when visible light is blocked by clouds or dust
   • Radar works by sending out microwave pulses from a transmitter mounted o the aircraft
   • Microwaves reflect from a metal target in a similar way to light rflecting off the mirror.
   • Example
     • An aircraft sends out a very brief microwaves pulse and receives an echo after 10.8 μs. If the speed of microwaves in air is 3.0 x 10(8) m/s, how far away is the target?
       • speed= Distance : time distance = speed x time =3.0 x 10(8) m/s x 10.8 μs = 3240m The distance to the target is half this, 1620m