12.2 + RP

Question 1

absorption and emission of infrared radiation required practical method

Answer 1

1. boil tap water in a kettle
2. using a measuring cylinder, add 200cm3 of water into each beaker
3. place the lid on the top of the beaker, push the thermometer through and clamp it so it does not touch the sides or bottom of the beaker
4. wait until the temperature on the thermometer stops rising
5. start the stopwatch. measure the temperature every 30s in each beaker for 15 minutes or until the temperature stops changing

Question 2

example of use of light waves

Answer 2

fibre optic communications

Question 3

if an object is hotter will it emit more or less infrared radiation

Answer 3

more

Question 4

what happens if infrared radiation is absorbed by the skin

Answer 4

can damage, burn, or kill skin cells because it heats up the cells

Question 5

infrared radiation uses

Answer 5

• remote control handsets because infrared pulses can be easily produced and detected electronically
• infrared cameras are used to see people and animals in the dark

Question 6

why are microwaves used for satellite tv

Answer 6

can pass through the atmosphere and reach satellites above the earth

Question 7

why are microwave ovens quicker at heating food than ordinary convection ovens

Answer 7

microwaves can penetrate into food and are absorbed by the water molecules in the food, heating it

Question 8

what type of wave do bluetooth enabled devices use

Answer 8

radio waves because they can communicate with each other over a range of 10 metres

Question 9

why can microwaves and radio waves be hazardous

Answer 9

they penetrate people’s bodies and can heat internal parts of the bod