(SP4) Waves

Question 1

Transverse waves -

Answer 1

particles move up and down as a wave passes - the particles are not carried to the shore (eg waves on the surface of water)

Question 2

Longitudinal waves -

Answer 2

particles move backwards and forwards as the wave passes. (eg sound)

Question 3

Wave speed =

Answer 3

frequency(Hz) x wavelength(m)

v=fλ

Question 4

Frequency =

Answer 4

1/T

T - period of time it takes for a wave ro do a complete cycle

Question 5

Measuring the speed of waves on sound:

Answer 5

1) Measure the distance between 2 fixed points
2) Measure the time it takes for one wave to travel between the 2 fixed points
3) Calculate speed using the equation

Question 6

Measuring the speed of sound

Answer 6

1) Measure the distance between you and the wall
2) Measure the time t takes for the echo of the sound to reach you
3) Double the speed and calculate the speed using the equation

Question 7

Transmitted -

Answer 7

the wave passes through the material and is not absorbed or reflected

Question 8

Absorbed -

Answer 8

the wave dissapears as the energy it is carrying is transferred to the material

Question 9

Human ears, describe how sound waves travel through our ears

Answer 9

1) Sound waves enter the ear canal
2) The eardrum is a thin membrance that sound waves make to vibrate
3) Vibrations are passed on to tiny bones which amplify the vibrations (make them bigger)
4) Vibrations are passed on to the liquid inside the cochlea.
5) Tiny hairs inside the cochlea detect these vibrations and create electrical signals - impulses
6) Impulses travel along neurones in the auditory nerve to reach the brain.

Question 10

How cochlea works?

Answer 10

The base of the cochlea is stiffer and detects very high frequencies. The apex of the cochlea is thinner and detects very low frequencies.
Each hair cell is connected to a neurone that sends signals to the brain.

Question 11

Ultrasound is…

Answer 11

sounds with frequencies more than 20000Hz

Question 12

What is ultrasound used for?

Answer 12

1) Sonar equipment measures the depth of the sea. A loudspeaker emits a pulse of ultrasound and a special microphone measure the time it between the sound being sent out and echo returning. The distance travelled is calculated by the formula (d=vt) and halved to find the depth.
2) Ultrasound scans. Ultrasound is used to make detailed images of unborn babies so that doctors can monitor how well the fetus developing. It is much safer than X-rays. A gel is used to stop the ultrasound just reflecting from the skin. The probe emits and receives ultrasound waves.

Question 13

Infrasound is…

Answer 13

sound with frequency less than 20Hz

Question 14

P waves -

Answer 14

are longitudinal waves, which means they can be transmitted through solids, liquids and gases. However, they can be reflected by something solid in the core and shadow zone is created.

Question 15

Shadow zone -

Answer 15

area where waves are not detected

Question 16

S waves -

Answer 16

are transverse waves, which means they can travel only through solid objects. S waves have a huge shadow zone because they do not travel through the core.