AQA GCSE Electromagnetic Waves Transferring Energy(Physics)
Electromagnetic Waves transferring energy.
Electromagnetic waves are transverse waves that transfer energy from the source of the waves to an absorber.
There are lots of different examples of this.
Radio waves transferring energy.
Radio waves propagate through space, including the air, from a transmitting aerial to a receiving aerial.
An alternating potential difference applied to the transmitting aerial causes an alternating current to flow, generating oscillating electric and magnetic fields that produce radio waves. These waves travel outward and, when absorbed by a receiving aerial, induce an alternating current with the same frequency as the radio wave, allowing signal reception. as shown below.
This will show the transfer of energy from a source to an absorber.
A radio transmitter converts electrical energy into radio waves.
These waves travel through air and are absorbed by a radio aerial in a receiver. This transfers energy from transmitting aerial to receiving aerial
The received energy is converted back into electrical signals and then into sound
Microwaves transferring energy.
A microwave oven generates microwaves, which penetrate food and cause water molecules to vibrate rapidly, increasing the thermal energy store of the water molecules.
This vibration increases thermal energy, heating the food.
Infrared Transferring Energy
All objects can emit Infrared radiation (heat energy). The higher the temperature of the object, the more Infrared radiation that is emitted.
The Sun would be an example of an object that emits IR, when the infrared is absorbed by a surface, the thermal energy of surface increases, warming the object. The IR is transferred by radiation, increasing the thermal energy store of the material.
Visible Light, transferring Energy.
The Sun emits visible light, which is absorbed by plants to power photosynthesis, converting light energy into chemical energy store (glucose).
Ultraviolet transferrring energy
UV light can also cause fluorescent materials to glow when they absorb the energy and re-emit it as visible light.
When UV light shines on a fluorescent material, it transfers energy to the material’s atoms and electrons. The electrons move from a lower energy level to a higher enegy level due to absorbing energy. Then these electrons fall back to a lower energy level and emit visible light, which is seen as fluorescence.
X-Rays transferring energy
X-ray machines emit X-rays, which pass through soft tissues but are absorbed by dense materials like bones.
This absorption creates an image on a detector, allowing doctors to see inside the body.
The X rays will carry the energy from the X ray machine to the person’s bones.
Gamma rays transferring energy.
Gamma rays carry high energy, which can kill cancer cells when directed at a tumor.
Practice Question
1.Where do electromagnetic waves transfer energy from and to?
2. Explain a radio broadcast can be an example of electromagnetic waves transferring energy
3. Suggest how Sunbathing would be an example of electromagnetic waves transferring energy.