Topic 4- Waves

Question 1

How do waves transfer energy

Answer 1

From one place to another without transferring any matter

Question 2

What happens when waves travel through a medium

Answer 2

The particles of the medium vibrate and transfer energy and information between each other. But overall particularly stay in the same place

Question 3

What is the amplitude of a wave

Answer 3

The displacement from the rest position to crest or trough

Question 4

What is wave length

Answer 4

Is the length of a full cycle of the wave

E.g. from crest to crest or from compression to compression

Question 5

What is the frequency of a wave

Answer 5

The number of complete cycles of the wave passing a certain point per second

Question 6

How is frequency measured

Answer 6

In hertz

Question 7

What is the period of a wave

Answer 7

The number of seconds it takes for 1 full cycle

Question 8

How do you work out period

Answer 8

Period = 1/frequency

Question 9

What ways are the vibrations of transverse waves

Answer 9

Sideways, vibrations are perpendicular (90 degrees)to the direction the wave travels

Question 10

Examples of transverse waves

Answer 10

All electromagnetic waves
S-waves
Ripples and waves in water

Question 11

What direction are the vibrations of longitudinal waves

Answer 11

Vibrations are Parallel to the direction the waves travel

Question 12

What are example of longitudinal waves

Answer 12

Sound waves

P-waves

Question 13

What do longitudinal waves do to the arrangement of particles

Answer 13

They squash up and stretch out the arrangement of particles in the medium they pass through making compressions (high pressure, lots of particles) and rarefactions (low pressure, fewer particles)

Question 14

How do you work out wave speed

Answer 14

Wave speed = distance/ time
V=x/t

Wave speed = frequency x wavelength
V=f λ

Question 15

How do you measure the speed of sound

Answer 15

Using an oscilloscope

Question 16

What do you add to a speaker so you can generate sound with a specific frequency

Answer 16

By attaching a signal generator to a speaker so you can generate sound with a specific frequency

Question 17

What do you use to find the wavelength of sound waves generated

Answer 17

Two microphones and an oscilloscope

Question 18

How does a oscilloscope measure the speed of sound

Answer 18

Attach a signal generator to a speaker so you can generate sounds with a specific frequency.
Use two microphones and an oscilloscope to find the wavelength of the sound waves generated

1. Set up the oscilloscope so that the detected waves at each microphone are shown as separate waves
2. Start with both microphones next to the speaker, then slowly move one away so the two signals are aligned on the display, but have moved exactly one wavelength apart
3. Measure the distance between the microphones to find one wavelength
4. Use the formula v=f λ to find the speed of the sound waves passing through the air - the frequency is whatever you set the signal generator to in the first place

Question 19

How do you measure the speed of water ripples using a strobe light

Answer 19

1. Using a signal generator attached to the dipper of a ripple tank you can create water waves at a set frequency
2. Dim the light and turn on the strobe lights - you’ll see a wave pattern made by the shadows of the wave crests on the screen below the tank
3. Alter the frequency of the strobe light until the wave pattern on the screen appears to ‘freeze’ and stop moving. This happens when the frequency of the waves and the strobe light are equal - the waves appear not to move because they are being lit at the same point in their cycle each time .
4. The distance between each shadow line is equal to one wavelength. Measure the distance between lines that are 10 wavelength apart, then find the average wavelength
5. Use v=f λ to calculate the speed of the waves

Question 20

How do you find the speed of waves in solids

Answer 20

By measuring the frequency of the sound waves produced when you hit the object
E.g. a rod with a hammer - the rod causes waves to be produced along the rod