Physics - 12 Wave Properties - Required Practical 8: Investigating Plane Waves in a Ripple Tank and Waves in a Solid

Activity 1: Investigating Plane Waves in a Ripple Tank

Aims:

  • use a ripple tank to measure the wavelength, frequency and speed of water waves

Risk Assessment:

Safety:

Equipment:

  • ripple tank and accessories (lamp, bar)

  • low-voltage supply

  • metre rule/ruler

  • white paper

  • video camera (with video editing software)

  • stopwatch

Control variables:

  • distance of lamp from ripple tank

  • distance of ripple tank from paper

Independent variable:

Dependent variable:

Method:

For the wavelength:

  1. Lay a ruler perpendicular to the shadows of the wavefronts on the white paper

  2. Using a video camera, record the waves moving past the ruler. Screenshot a still image from the video

  3. Find the wavelength of one wave by dividing the length of 10 wavelengths by 10

For the frequency:

  1. Place the stopwatch next to the setup of ruler and ripple tank. Draw an arrow on the white paper at a fixed point

  2. Start to record a video of the setup. Start the stopwatch and let it run for 10 seconds, then stop filming

  3. Put the video in slow motion and count the number of waves that pass the arrow in the 10 seconds. Find the frequency of the waves by dividing this by 10

Calculations & graphing:

  • calculate the speed of the waves using v = fλ (multiplying together the two values recorded)

Activity 2: Investigating Waves in a Solid

Aims:

  • measure the wavelength, frequency and speed of waves in a solid

Risk Assessment:

Safety:

Equipment:

  • vibration generator

  • power signal generator

  • string/elasticated cord

  • wooden bridge

  • pulley on a clamp

  • masses and hanger

  • metre rule

Control variables:

Independent variable:

Dependent variable:

Method:

  1. Turn on the signal generator to cause the string to vibrate. Adjust the frequency until you reach a standing wave of one wavelength. Record this frequency

  2. Using the metre rule, measure the distance from the wooden bridge to the vibration generator. This is the wavelength of the wave

Calculations & graphing:

  • calculate the speed of the waves using v = fλ (multiplying together the two values recorded)