REQUIRED PRACTICAL: THE RIPPLE TANK

Question 1

How do you measure the frequency of the waves accurately?

Answer 1

• frequency is the number of waves passing a point in a second
• timing for 1 second causes inaccurate results, so set a timer for 10 seconds and count the number of waves passing in that time
• then divide the number by 10 to find the number in 1 second - this is frequency

Question 2

How do you measure the wavelength of the waves accurately?

Answer 2

• wavelength is the distance between a point on a wave and the same point on the adjacent wave
• place a metre rule on the floor screen, at right angles to the waves and measure the length of at least 3 waves (just measuring 1 would be inaccurate)
• divide the length by the number of waves to give wavelength

Question 3

How do you calculate the speed of the waves?

Answer 3

• use the methods described already to determine the frequency and the wavelength of the wave
• now use the equation:
  wave speed = frequency x wavelength
• and multiply the two numbers together to find the wave speed

Question 4

What is another way of determining the speed of a wave?

Answer 4

• measure the time it takes for a wave to cross the screen using a stopwatch
• now measure the distance the wave has travelled with a ruler (this is the length of the screen)

Now use the equation:
speed = distance ÷ time

• and divide the distance by the time to find the wave speed