Waves (6) - Pt3

Question 1

What emits infrared?

Answer 1

-all objects are continually emitting ans absorbing infrared radiation. It emitted from the surface of the object

Question 2

How much infrared an object emits depends on what?

Answer 2

• the hotter an object the more infrared it radiates
• an object hotter than its surroundings emits more IR radiation than it absorbs as it cool down
• an object cooler than its surroundings absorbs more IR than it emits as it warms up
• objects at constant temperature emit and absorb infrared radiation at the same rate
• some colours & surfaces are better at absorbing and emitting radiation

Question 3

What surfaces are the best surfaces from absorbing and emitting radiation and which are the worst?

Answer 3

• best: black and Matt

- worst: white and shiny

Question 4

What’s a perfect black body?

Answer 4

• an object that absorbs all of the radiation that hits it.
• It doesn’t reflect or transmit any radiation.
• a good absorber is also a good emitter, a perfect black body would be the best possible emitter.

Question 5

What does the temperature oft he earth depend on?

Answer 5

• the amount of radiation it emits, absorbs ans reflects
• during the day light is absorbed from the sun
• at night less radiation is being absorbed than emitted

Question 6

How do sound waves travel?

Answer 6

• sound waves cause vibrations a series of rear fractions and compression (they’re longitudinal waves)
• they travel fastest in solids and cause the particles to vibrate

Question 7

What’s the human sound range?

Answer 7

20 Hz to 20 kHz

Question 8

How do ears work?

Answer 8

• sound waves cause the ear drum to vibrate
• the vibrations pass to the ossicles and then to the cochlea
• the cochlea turns there’s vibrations into electrical signals and sends the to your brain
• human hearing is limited by the size and shape of our ear drums

Question 9

What happens when sound waves are reflected?

Answer 9

(Reflected by hard flat surfaces)

-echos are reflected sound waves

Question 10

What are the properties of ultra sound?

Answer 10

• has a frequency higher than 20 000 Hz
• it gets partially reflected at boundaries (some of the wave is reflected and the rest is transmitted), so it can measure how far away something is

Question 11

Explain how ultra sound can be used medically?

Answer 11

• pre-natal scanning of a foetus
• it’s partially reflected back and detected when it reaches the fluid if the womb
• it’s safer then x-rays

Question 12

Explain how ultrasound can be used for industrial imaging?

Answer 12

• finding flaws in materials

- ultrasound waves are usually reflected from either side of the material if there’s a crack it will reflected sooner

Question 13

What’s echo-sounding?

Answer 13

• it uses high frequency sound waves (including ultrasound)

- used by boats ams submarines to find out the depth of wanted or to locate objects in deep water

Question 14

How do you detected seismic waves?

Answer 14

Seismographs

Question 15

What are the 2 types of seismic waves?

Answer 15

P-waves and S-waves

Question 16

What are the properties of P-waves?

Answer 16

P-waves are longitudinal
They travel through solids and liquids
They’re faster then S-waves

Question 17

What are the properties of S-waves?

Answer 17

They’re transverse
Can’t travel through liquids or gases
Slower than P-waves

Question 18

How have S and P waves helped?

Answer 18

Our current understanding of the internal structure if the earth and size if the earths core is based of observations of P and S waves
Crust 
Solid-ish mantle 
Liquid outer core
Solider inner core