Ripple Tank

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ripple tank

The ripple tank is used to generate water waves in laboratory. It is useful in demonstrating wave properties such as reflection and refraction. It consists of a shallow tray of water with a transparent base, a light source directly above the tray and a white screen beneath the tray to capture the image of the shadows formed when water waves spread across the tank as shown above. Straight waves can be set up by using a straight dipper, while circular waves can be formed by using a spherical dipper. Both dipper are vibrated up and down by a motor.

The waves will be seen in bright and dark patches on the screen below the tray. These patches show the position of the crests and troughs of the waves. The dark patches will correspond to the crests and bright patches will be the troughs.

 

Why does the dark patches correspond to the crests and bright patches correspond to the troughs?

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Light is absorbed/scattered as it passes through a body of water. At a crest, the light has to travel a longer distance through the water, which will cause more light to be absorbed/scattered. This will cause crests to appear as dark patches. The opposite logic applies to the troughs. At a trough, the light travels a shorter distance through the water, which causes less light to be absorbed/scattered. This causes troughs to appear as bright patches.

 

Video of a ripple tank in action

 


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15 thoughts on “Ripple Tank”

  1. How can the waves in ripple tank be made to travel more slowly and when this happen,what will be its effect on frequecny and wavelenght of the waves?

    Reply
  2. While studying waves in ripple tank,crest of the wave appear as bright line and trugh appear as black portion .why .Give reason plz

    Reply
  3. Mini physics is the best
    It is helping me a lot
    Its easy to understand
    Keep up with the good work because its very helpful

    Reply
    • The ripple tank shows the crests and trough of the water wave – a transverse wave. From this, you can deduce the wavelength, frequency and period of the water wave. Since longitudinal waves can be modelled with a transverse wave, you can deduce the motion of a longitudinal wave as well.

      Reply

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