Microwaves (T3)

Question 1

Describe microwaves and how microwave ovens work…

Answer 1

• the only thing that exposure to microwaves really heats up is the water molecules within the matter being heated
• the energy from microwaves is transferred directly to the water molecules causing them to heat up

Question 2

Why can you not heat things such as eggs up in microwaves?

Answer 2

• as a microwave oven heats up water molecules, it causes expansion of steam into the cavity within the microwave itself

Question 3

Why do microwaves not make food crispy on the surface?

Answer 3

They affectively cook the food from within, unlike infrared radiation which penetrates and slowly heats the food from the outside

Question 4

Aside from cooking, what are microwaves used for?

Answer 4

• microwave radiation can be used to transmit signals such as those for mobile phone calls
• microwave transmitters and receivers on buildings and masts communicate with the mobile phones in their range

Question 5

List three uses of microwaves…

Answer 5

• cooking
• communications
• satellite transmissions

Question 6

How do microwaves work within communications?

Answer 6

• microwaves pass easily through the Earth’s atmosphere and so are used to carry signal to orbiting satellites
• from here the signal are passed onto their destination or onto other orbiting satellites
• messages between mobile phones are also carried by microwaves