Microwaves
4 marks · NormalMicrowaves are part of the electromagnetic spectrum and have a wide range of applications.
Explain why microwaves are used to send signals to and from satellites, rather than radio waves.
Describe one reason why microwave ovens cook food differently compared to conventional ovens.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) Microwaves can pass through Earth’s atmosphere and clouds more easily than most radio waves, so they are suitable for satellite communication.
(b) Microwaves heat food by directly causing water molecules in food to vibrate and heat up, cooking food from the inside rather than just the outside, as in conventional ovens.
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · States that microwaves can pass through the atmosphere/clouds.
A1 (a) · 1 mark · Links passing through atmosphere to suitability for satellite communication.
M2 (b) · 1 mark · States microwaves are absorbed by water molecules in food.
A2 (b) · 1 mark · Mentions food is cooked from inside as a result, unlike conventional ovens.
Worked solution
a) Microwaves are chosen for satellite communication because they can pass through the Earth's atmosphere and clouds, which most radio waves cannot easily do. This makes them ideal for transmitting signals to and from satellites in orbit.
b) Microwave ovens use microwaves that are absorbed by water molecules in the food. This causes the molecules to vibrate and generate heat throughout the food, so microwaves cook food from the inside as well as the outside. Conventional ovens mainly heat the outside using infrared radiation and conduction.