• Question: What is an echo?

    Asked by anon-267489 to Louisa, Katherine, Iain, Eleanor, David, Bradley, Adrien on 26 Nov 2020.
    • Photo: Katherine Manfred

      Katherine Manfred answered on 26 Nov 2020:

      Sound is made up of pressure waves – kind of like how light is actually electromagnetic waves. When it hits a stiff, flat surface, the pressure waves bounce off in a similar way to light bouncing off a mirror surface or water waves hitting a rock. The echo we here is these pressure waves reflected back at us (and picked up by our ears)

    • Photo: Adrien Chauvet

      Adrien Chauvet answered on 26 Nov 2020:

      The most common echo is with sound (e.g. sound bouncing back against a wall), but you can also have:
      – nuclear spin-echo, which is a rephasing of the spins of the atom’s nucleus. We use it in NMR.
      – photon echo, which is similar to the previous, but with light! We use it to understand who molecules behaves in -extremely- short time scales (~10^-12 sec).

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