properties of waves (topic 6)

Question 1

describe one similarity and a difference between longitudinal and transverse waves (2)

Answer 1

• both transfer energy without transferring matter
• both involve continuous oscillations
• longitudinal waves have oscillations parallel to the direction of wave motion (energy transfer)
• and transverse waves have oscillations perpendicular to the direction of motion (energy transfer)

Question 2

give an example of a transverse wave (1)

Answer 2

• em - radio, ultraviolet, X-ray
• water waves

Question 3

define the term time period of a wave (1)

Answer 3

time taken for one complete wave, measured in seconds

Question 4

calculate the frequency of the waveform with a period of 16ms

Answer 4

Question 5

Answer 5

Question 6

sketch a labelled diagram of a longitudinal wave

Answer 6

Question 7

describe the movement of particles in a longitudinal wave relative to the direction of energy transfer (1)

Answer 7

oscillations are parallel to the direction of energy transfer

Question 8

give and example of a longitudinal wave

Answer 8

• sound
• ultrasound
• seismic P-waves

Question 9

calculate the wavelength

Answer 9

• 90 cm = 1.5 waves
• wavelength = 90 ÷ 1.5 = 60 cm

Question 10

the student increases the frequency output of the signal generator and decreases the amplitude, the student moves the wooden bridge until 3 peaks are seen again, describe how the observed pattern will be different to the one in the diagram (2)

Answer 10

• the height of the wave will be smaller
• the wavelength is shorter, peaks are closer together

Question 11

transverse waves have oscillations

Answer 11

perpendicular to the direction of energy transfer

Question 12

describe the movement of the buoy as the water passes it (2)

Answer 12

• water waves are transverse
• the buoy will move up and down as the water rises and falls

Question 13

describe how a ripple tank creates waves that can be observed on a piece of paper below the ripple tank (3)

Answer 13

• when the power supply is turned on it causes the bar in the ripple tank to vibrate in the water
• this sets up waves in the water
• a light source above the ripple tank projects an image of the wavefronts onto the paper below

Question 14

the accepted value for the speed of sound in air is 330 m/s, explain why the students value is different, lower, to this value (2)

Answer 14

• recorded times are very small
• therefore reaction time will increase the uncertainty of the time measurements

Question 15

describe how the student could reduce the uncertainty in their experiment but use the same equipment (2)

Answer 15

• increase the distance between the two students
• so that reaction time is less significant

Question 16

16 ms in seconds

Answer 16

0.016 s