# P5.1 - Wave Behaviour Flashcards

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1
Q

What is a wave? (2)

A

an oscillation that transfers energy (1) without transferring matter (1)

2
Q

how do sound waves transfer energy?

A

They transfer energy by the molecules vibrating and knocking into neighbouring molecules

3
Q

How do phones communicate ?

A

Using Electromagnetic waves (microwaves if ur being specific)

4
Q

define amplitude

A

the distance from the middle of a wave to the crest or trough

5
Q

Define Wavelength

A

distance from one peak (or trough) to the next peak (or trough) in m

6
Q

define time period

A

the time for one wave to pass a given point or the time for one complete oscillation in seconds (s)

7
Q

define frequency

A

the number of peaks passing a point per second (measured in Hz)

8
Q

What is a rarefaction?

A

A part of a longitudinal sound wave which has low pressure (wide bits - particles spread far apart)

9
Q

what is a compression?

A

a part of a longitudinal wave where the pressure is high

close together lines - because particles are squashed together

10
Q

state 1 example of mechanical waves

A

sound waves

11
Q

what is a mechanical wave?

A

a wave that needs medium or matter to travel through

12
Q

do electromagnetic waves require medium/matter to travel through?

A

no they do not, can travel through vacuum

13
Q

state an example of longitudinal waves

A

sound waves

14
Q

describe the way transverse waves travel

A
• direction of vibration is perpendicular to the direction of travel of the wave
15
Q

describe one way to model waves

A
• ripples on water
TRANSVERSE WAVE
(surface of water moves up and down, waves travel, water does not) - showed by cork
16
Q

does air move when sound waves move?

A

no - sound is transferred through vibrating molecules, which stay where they are and vibrate about a fixed point

17
Q

what does a time trace diagram do?

A
• shows how displacement of a wave varies with time

- let us to measure the time period from any point on a wave to point in next

18
Q

what is the equation to find out the time period?

A

1
———
frequency

19
Q

what is the x-axis label on a snapshot diagram?

A

distance travelled

20
Q

what is the x-axis label on a time trace diagram?

A

time (in seconds)

21
Q

what is the formula for wave speed?

A

s = f x w

22
Q

what is the equation to measure wave speed?

A

Wavelength (m) x Frequency (hz)

23
Q

difference between transverse and longitudinal waves (vibration of particles in terms of direction of travel)

A
• transverse = vibrations at right angles of direction of travel
• longitudinal = vibrations at same direction to direction of travel
24
Q

considering what kind of wave light travels as, is it a mechanical wave?

A

light travels as an electromagnetic wave

- so no, it is not a mechanical wave as it can travel without a medium (CAN TRAVEL IN A VACUUM)

25
Q

why can longitudinal waves pass through faster in a solid compared to a gas?

A

as particles are very close together, so vibrations can be passed on very fast (faster wave speed)

26
Q

how is the amplitude related to the amount of energy a wave carries?

A

bigger amplitude = more energy the wave carries

27
Q

how are frequency and wavelength connected?

A

bigger wavelength = smaller frequency

28
Q

what is the equivilant to peaks and troughs in a longitudinal wave?

A

compressions (peaks)

rarefractions (troughs)

29
Q

how are ripples on water surfaces used to model transverse waves

A
• if cork placed on the surface, it is not carried by the wave (only moves up and down)
• ripples travel perpendicular to energy transfer
30
Q

how can the speed of a transverse wave be measured using a ripple tank

A

1) light shone through tank
2) dark + light patches appear underneath it as light passes through crests + troughs
3) count number of times a dark patch passes through a point in a minute, divide by 60 = frequency
4) measure wavelength by the distance between each dark patch between waves
5) then use v = f x w to calculate speed

alternatively, to reduce systematic errors:
It can be difficult to identify the wavefronts while they are moving
Use a stroboscope (flashing light) matched to the same frequency of the waves, this will be indicated by the waves appearing to be stationary
The frequency can be read from the frequency setting of the stroboscope, and the wavelength will be easier to determine while the waves appear still