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EM Waves and their Uses

Microwaves are used by satellites

  • Communication to and from satellites uses microwaves. But you need to use microwaves which can pass easily through the Earth’s watery atmosphere

  • For satellite TV, the signal from a transmitter is transmitted into space where it’s picked up by the satellite receiver dish orbiting thousands of kilometres above the Earth. The satellite transmits the signal back to Earth in a different direction

  • It is then received by a satellite dish on the ground. There is a slight time delay between the signal being sent and received because of the long distance the signal has to travel

Microwave ovens use a different wavelength from satellites

  • In communications, the microwaves used need to pass through the Earth’s watery atmosphere

  • In microwaves ovens, the microwaves need to be absorbed by water molecules in food-so they is a different wavelength to those used in satellite communications

  • The microwaves penetrate up to a few centimetres into the food before being absorbed and transferring the energy they are carrying to the water molecules in the food, causing the water to heat up

  • The water molecules then transfer this energy to the rest of the molecules in the food by heating-which quickly cooks the food

Infrared radiation can be used to increase or monitor temperature

  • Infrared radiation is given out by all hot objects, and the hotter the object, the more IR radiation it gives out

  • Infrared cameras can be used to detect infrared radiation and monitor temperature. The camera detects the IR radiation and turns it into an electrical signal, which is displayed on a screen as a picture. The hotter an object is, the brighter it appears

  • Absorbing IR radiation causes objects to get hotter. Food can be cooked using IR radiation, the temperature of the food increases when it absorbs IR radiation

  • Electric heaters heat up a room in the same way. Electric heaters contain a long piece of wire that heats up when a current flows through it. This wire then emits lots of infrared radiation. The emitted IR radiation is absorbed by objects and the air in the room-energy is transferred by the IR waves to the thermal energy stores of the objects, causing their temperature to increase

EM Waves and their Uses

Microwaves are used by satellites

  • Communication to and from satellites uses microwaves. But you need to use microwaves which can pass easily through the Earth’s watery atmosphere

  • For satellite TV, the signal from a transmitter is transmitted into space where it’s picked up by the satellite receiver dish orbiting thousands of kilometres above the Earth. The satellite transmits the signal back to Earth in a different direction

  • It is then received by a satellite dish on the ground. There is a slight time delay between the signal being sent and received because of the long distance the signal has to travel

Microwave ovens use a different wavelength from satellites

  • In communications, the microwaves used need to pass through the Earth’s watery atmosphere

  • In microwaves ovens, the microwaves need to be absorbed by water molecules in food-so they is a different wavelength to those used in satellite communications

  • The microwaves penetrate up to a few centimetres into the food before being absorbed and transferring the energy they are carrying to the water molecules in the food, causing the water to heat up

  • The water molecules then transfer this energy to the rest of the molecules in the food by heating-which quickly cooks the food

Infrared radiation can be used to increase or monitor temperature

  • Infrared radiation is given out by all hot objects, and the hotter the object, the more IR radiation it gives out

  • Infrared cameras can be used to detect infrared radiation and monitor temperature. The camera detects the IR radiation and turns it into an electrical signal, which is displayed on a screen as a picture. The hotter an object is, the brighter it appears

  • Absorbing IR radiation causes objects to get hotter. Food can be cooked using IR radiation, the temperature of the food increases when it absorbs IR radiation

  • Electric heaters heat up a room in the same way. Electric heaters contain a long piece of wire that heats up when a current flows through it. This wire then emits lots of infrared radiation. The emitted IR radiation is absorbed by objects and the air in the room-energy is transferred by the IR waves to the thermal energy stores of the objects, causing their temperature to increase