p12

Question 1

what is a transverse wave?

Answer 1

waves where the points along its lengths vibrate at 90 degrees to the direction of energy transfer
eg: ripples on the surface of water, electromagnetic waves

Question 2

what is a longitudinal wave?

Answer 2

waves where the points along its length vibrate parallel to the direction of energy transfer.
eg: sound waves, pressure waves caused by repeated movements in a liquid or a gas

Question 3

differences between longitudinal and transverse waves

Answer 3

transverse waves have
- peaks and troughs,
- their vibrations are 90 degrees to the direction of energy transfer,
- only electromagnetic waves can travel in vaccum,
- they can move in liquids and solids, but not gases,
- constant density and pressure

Question 4

what is the amplitude of the wave?

Answer 4

maximum displacement of a point on a wave from its undisturbed position

Question 5

what is the wavelength of a wave

Answer 5

the distance from a point on one wave to the equivalent point on the adjecant wave

Question 6

what is frequency of wave?

Answer 6

the number of waves passing a point each second

Question 7

what is range of human hearing and why can they not hear outside this range?

Answer 7

20Hz to 20kHz.
The conversion of sound waves to vibrations of solids works over a limited frequency range.
This restricts the limits of human hearing

Question 8

how do u hear sound?

Answer 8

Within the ear, sound waves cause the ear drum and other parts to vibrate which causes the sensation of sound.

Question 9

what is the purpose of the ripple tank in the experiment?

Answer 9

to create small waves in water

Question 10

what is the purpose of the light source in the experiment?

Answer 10

to illuminate the waves to create shadows

Question 11

what is the purpose of the white sheet of paper in the experiment ?

Answer 11

to provide a white backgound yo act as a screen for the wavefront shadows

Question 12

ripple tank experiment steps

Answer 12

• Set up the apparatus as shown and fill the ripple tank with water to a depth of no more than 1 cm
• Turn on the power supply and the light source to produce a wave pattern on the screen
• The wavelength of the waves can be determined by using a ruler to measure the length of the screen and dividing this distance by the number of wavefronts
• The frequency can be determined by timing how long it takes for a given number of waves to pass a particular point and dividing the number of wavefronts by the time taken
• Record the frequency and wavelength in a table and repeat the measurements

Question 13

define reflection

Answer 13

when a wave hits a boundary between two media and does not pass through, but instead stays in the original medium

Question 14

define transmission

Answer 14

when a wave passes through a substance

Question 15

define absorption

Answer 15

energy is transferred from the wave into the particles of a substance

Question 16

what are some uses of sound waves?

Answer 16

echo sounding - used by ships to detect the ocean floor
ultrasound - looking inside human body
seismic activity - to investigate the structure of the earth

Question 17

what is ultrasound?

Answer 17

sound waves with a frequency above the human hearing range

Question 18

how is ultrasound used for detection?

Answer 18

they are partially reflected when they meed a boundary between two different media.
the time taken for the reflections to reach a detector can be used to determine how far away sich a boundary is

Question 19

echo sounding

Answer 19

uses ultrasound to detect objects underwater
- the sound is reflected off the ocean bottom.
- the time it takes for the soundwave to retur is used to calculate the depth of the water

Question 20

ultrasound in medicine

Answer 20

used to
- construct an image of foetus in womb
- to generate images of organs and internal structures
- as medical treatment such as removing kidney stones

Question 21

what are P waves

Answer 21

they are longitudinal seismic waves
they travel at different speeds through liquids and solids

Question 22

what are S waves

Answer 22

transverse seismic waves and cannot travel through a liquid