waves

Question 1

what are transverse waves?

Answer 1

oscillations are perpendicular to the direction of energy transfer ex. ripples + waves in water

Question 2

what are longitudinal waves?

Answer 2

• oscillations are parallel to the direction of energy transfer - ex. sound waves in air
• show areas of compression and rarefaction

Question 3

how to calculate wave speed?

Answer 3

wave speed = frequency x wavelength

wave speed = m/s
frequency = Hz
wave length = m

Question 4

what happens when waves travel through a medium?

Answer 4

• when waves travel through a medium the particles of the medium oscillate and transfer energy between each other
• but - particles stay in same place - only energy transferred

Question 5

how to find period of wave?

Answer 5

T = 1/f
period = s
frequency = Hz

Question 6

how to measure the speed of ripples using a ripple tank?

Answer 6

• using signal generator attached to dipper of a ripple tank - can create water waves at set frequency
• dim lights in lab and turn on lamp - should see wave crests as shadows on screen below tank
• distance between each shadow line equal to one wavelength - measure distance between shadow lines that are 10 wavelengths apart - divide distance by 10 to find wavelength
• good method for measuring wavelength of moving waves or small wavelengths

Question 7

ripple tank: application

Answer 7

• calculate wavespeed of waves

- set-up suitable as allows to measure wavelength without disturbing waves

Question 8

what happens when a wave meets a boundary?

Answer 8

• when a wave meets a boundary between two materials it can be absorbed, transmitted or reflected
• what actually happens depends on the wavelength of the wave + properties of materials involved

Question 9

what happens when a wave is absorbed by a second material?

Answer 9

• when wave is absorbed by second material - wave transfers energy to material’s energy stores - often to thermal energy store - leads to heating

Question 10

what happens when a wave is transmitted by a second material?

Answer 10

• when a wave is transmitted through second material - wave carries on travelling through new material - often leads to refraction - can be used in communications, lenses in glasses + cameras

Question 11

what happens when a wave is reflected by a second material?

Answer 11

where incoming ray neither absorbed or transmitted - instead ‘sent back’ away from second material - how echoes created

Question 12

what are EM waves?

Answer 12

• electromag waves are transverse
• transfer energy from a source to an absorber
• travel at the same speed through air or a vacuum
• arent vibrations of particles - vibrations of electric + mag fields - means can travel through vacuum
• travel at diff speeds in diff materials - can lead to refraction
• EM waves can vary in wavelength from around 10-15m to more than 10 4m

Question 13

what is the EM spectrum?

Answer 13

• grouped based on wavelength + frequency - seven basic times - but diff groups merge to form a continuous spec
• eyes can only detect small part of spec - visible light

Question 14

why is there a large range if frequencies in the EM spec?

Answer 14

• EM waves generated by variety of changes in atoms + their nuclei
• also explains why atoms can absorb a range of frequencies - each one causes a different change
• because of different properties, different EM waves used for diff purposes

Question 15

spec

Answer 15

• radio waves 1m - 10 4m
• micro waves - 10-2m
• infrared 10-5m
• visible light 10-7m
• ultra violet 10-8m
• x-rays 10-10m
• gamma rays 10-15m