P5.1 + 2 - Waves

Question 1

Longitudinal waves

Answer 1

Series of rarefactions and contractions that go parallel to propagation that transfer particles

Question 2

Transverse waves

Answer 2

Travel at a right angle to propagation and do not transfer particles

Question 3

Amplitude

Answer 3

Distance from top to middle of a wave

Question 4

Wavelength

Answer 4

Distance from one point of wave to the next identical

Question 5

Frequency

Answer 5

No. of waves per second 1/T

Question 6

Time period

Answer 6

Time for one wave to pass in given time 1/F

Question 7

Wave velocity equation

Answer 7

Velocity (m/s) = wavelength (m) * frequency (Hz)

Question 8

Velocity of ripples

Answer 8

• find wavelength using strobe band ruler
• fine frequency by no. of rotations per second of motor
• apply equation

Question 9

Velocity of wave changes

Answer 9

When travelling through different mediums called refractions

Question 10

Travelling through solids

Answer 10

Increases velocity because more particles are able to vibrate

Question 11

What can happen to sound

Answer 11

• reflected
  -transmitted (refracted)
  -absorbed

Question 12

ultrasound frequency

Answer 12

20KHz

Question 13

How does ultrasound work

Answer 13

• transmitter beams ultra waves
  -waves reflect at different boundaries
• machine calculates distance from SDT to produce image

Question 14

Ear detect sound

Answer 14

• waves travel through auditory canal to ear drum
  -drum vibrates and passes to ossicles (hammer anvil and stirrup)
• act as lever to amplify vibrations
• through into cochlea where hairs vibrate
  -vibrations to auditory nerve where brain converts to sound

Question 15

Short hairs in cochlea

Answer 15

Vibrate at high frequencies

Question 16

Long hairs in cochlea

Answer 16

Vibrate at small frequency

Question 17

As you get older…

Answer 17

You lose cochlea hair (short ones) which makes it harder to hear high frequency

Question 18

EM spectrum

Answer 18

-radio
-micro
-infrared
- visible
-uv
-xrays
-gamma

Question 19

Which em wave has highest wavelength

Answer 19

Radio

Question 20

Which em has largest frequency

Answer 20

Gamma

Question 21

Em velocity

Answer 21

3.0 * 10^8 m/s

Question 22

How to produce radio waves?

Answer 22

-oscillating pd across wire makes electrons move forward and back
-Produces changing elec and mag field as radio wave
-when connected creates em wave by moving electrons

Question 23

Uses of waves

Answer 23

Radio - radio stations
Microwave - Wi-Fi and ovens
Infrared - cooking food
Visible - light or torches
UV - produce vitamin and kill bacteria
X-rays - kill skin cancer
Gamma - kill cancer and bacteria

Question 24

Danger of em

Answer 24

UV - damage skin cells by growing very rapidly
X-rays - cause skin cancer
Gamma - kill cells in body

Question 25

How is infrared imaging

Answer 25

Uses thermo imaging camera to absorb infrared waves and produce image

Question 26

How is X-ray imaging

Answer 26

Solid body parts absorb waves and produce image

Question 27

How is gamma imaging

Answer 27

Injects a patient with radioactive substance that emits gamma rays

Question 28

As you go into the rainbow

Answer 28

Frequency increases + wavelength decreases