P6: MEASURING WAVE SPEED

Question 1

What is the equation linking velocity frequency and wavelength?

Answer 1

velocity (m/s) = frequency (Hz) x wavelength (m) (V = f λ)

Question 2

RP - Measuring wave speed using a string: method

Answer 2

-turn on vibration generator so string starts to vibrate
-adjust tension in the string until a loop wave pattern can be seen
-record frequency shown on vibration generator
-use a metre ruler to measure the full length of the string
-count the number of loops on the string
-divide the full length by the number of loops and multiply by 2 to give the wavelength
-calculate speed of the wave using V = fλ

Question 3

RP - Measuring wave speed using a ripple tank: method

Answer 3

-adjust height of the wooden rod so that it touches the edge of the water
-switch on the motor so that low frequency waves are produced
-turn on the lamp and place white card under the tank so the waves can clearly be seen
-use a metre ruler to measure across 10 waves and divide this length by 10 to measure the length of the waves
-count the number of waves passing a point in the pattern over 10s and divide by 10 to give frequency of the waves
-calculate wave speed using V = f λ