P12 - Wave Properties

Question 1

What categories of waves do all waves fall under

Answer 1

Either transverse or longitudinal

Question 2

Direction of oscillations to energy transfer in transverse waves

Answer 2

The oscillations are perpendicular to the direction of energy transfer
The direction of energy transfer is sideways but the oscillations go up and down

Question 3

What do longitudinal waves have that transverse waves don’t

Answer 3

• They have compressions (regions with lots of particles) and rarefactions (regions with less particles)

Question 4

Direction of oscillations to energy transfer in longitudinal waves

Answer 4

The oscillations are parallel to the direction of energy transfer

Question 5

Do longitudinal or transverse waves need a medium to travel

Answer 5

All logitudinal waves do but not all transverse waves do

Question 6

What is the amplitude of a wave

Answer 6

The maxium displacement of a point on a wave away from its undisturbed position

Question 7

What is the wavelength of a wave

Answer 7

The distamce from one point on one wave to the equivalent point on the adjacent wave
It is measured in lambda (λ)

Question 8

What is the frequency of a wave

Answer 8

The number of waves passing a point each second
It is measured in Hertz (Hz)

Question 9

What is the period of a wave and its equation

Answer 9

The time it takes for one wave to pass a certain point
period (s) = 1/frequency
(T = 1/f)

Question 10

What is the wave speed

Answer 10

The spped at which the wave moves through the medium (the speed of energy transfer as waves transfer energy, not matter)

Question 11

Equation for wave speed

Answer 11

v = fλ
wave speed(m/s) = frequency(Hz) x wavelength(m)

Question 12

Method to find the speed of sound waves in air

Answer 12

• Seperate 2 people by 500m on a flat area
• Give one a pair of cymbals and the other a stopwatch
• Person A clashes the cymbals together and Person B start the timer when they see this happening
• Person B stops the stopwatch when they hear the cymbal crash
• To find the speed, you divide the distance by the time

Question 13

Problems with the method to find the speed of sound waves and fixes

Answer 13

• Everyone has a different reaction time - it takes time between seeing the cymbals and starting the timer and then hearing the sound and stopping the timer
• This can be reduced by having lots of people with timers to discount anomalies and find a emean
• The time between seeing and heaaring is very short - this can be reduced by using a larger distance

Question 14

What 3 things could happen when a wave hits a boundary between two different materials

Answer 14

• It could be transmitted (includes refraction)
• The energy of the wave could be absorbed
• The surface of the material could reflect the wave

Question 15

What happens to a wave when it travels from one medium to another

Answer 15

• Its speed and wavelength change and they are directly proportional
• But its frequency stays the same because the source is producing the same amount of waves per second

Question 16

Relationship between the angles of reflection and incidence

Answer 16

they are the same

Question 17

How does the ear work to help us hear sound

Answer 17

• Sound waves are funneled into the ear canal and hit the ear drum
• The sound waves cause the ear drum to vibrate
• The conversion of sound waves to vibration only happens over a limited frequency however

Question 18

Range of normal human hearing

Answer 18

20 - 20000Hz

Question 19

What do the frequency and amplitude of sound waves represent

Answer 19

• Frequency is the pitch. High frequency means high pitched
• Amplitude is the volume. A large amplitude means a loud sound

Question 20

What is a reflected sound wave called

Answer 20

An echo

Question 21

What is ultrasound

Answer 21

Sound waves with a frequency higher than the upper limit of human hearing
They partially reflect at the boundary between two densities

Question 22

Uses of ultrasound

Answer 22

The time taken for an ultrasound relfection can be measured using a detector
This means it can be used in medical and industrial imaging e.g. to see organs or metal defects

Question 23

What are P waves

Answer 23

Longitudinal waves than can pass through liquids and solids, They aslo travel faster than S waves

Question 24

What are S waves

Answer 24

Theya re transverse waves that can only travel through solids

Question 25

How do seismic waves provide evidence of the internal structure of the earth

Answer 25

• S waves can only be detected on certain parts of the crust and there is an S wave shadow zone
• This is because S waves cannot pass through liquids so the Earth must wave a liquid core
• There are also P wave shadown zones and this is due to P waves travelling faster in solids than liquids
• This causes them to refract in the liquid outer core