• Question: If salt in water conducts electricity, how come when lightning strikes the water, all of the fish don't die?

    Asked by Paul mackie no 2 to Greg, Jen, Laura, Mobeen, Paul on 9 Mar 2016.
    • Photo: Paul O'Mahoney

      Paul O'Mahoney answered on 9 Mar 2016:

      You are right that salt water is very conductive, and that is part of the reason that some fish stay safe. When lightning strikes the water, it is conducted very well but only so far, and mostly across the surface. Any fish very close to the surface will maybe die 🙁 but because the salt water is such a good conductor, the elctricity prefers to travel through the water than the fish so many fish further down can still survive

    • Photo: Greg Melia

      Greg Melia answered on 9 Mar 2016:

      The reason why you die if you get hit by lightning is that the lightning is using you as a conductor (effectively a wire) to flow between the cloud and the ground. It wants to flow to ground because the cloud is at a much higher potential (higher energy level) than the ground and it wants to lose some of that energy. You’re the easiest way of it getting down there, so most of the energy flows through you – which is very bad news!

      Once the energy has reached the earth, it can spread out. This will ‘dilute’ it, so not a lot of the energy will actually flow through the fish.

      What Paul says is also true: the sea is a good conductor, so most of the energy flows through the sea instead of the fish. If you watch the video in the link, a guy in a cage gets hit with lightning but lives: although there are holes in the cage, the metal of the cage is a much better conductor than the man, so the man doesn’t have any electricity flow through him.

    • Photo: Jen Lowe

      Jen Lowe answered on 9 Mar 2016:

      This is a great question – you have a great inquisitive mind. I’m going to guess here…
      Death from electrocution happens when the electricity passes through a body and ?stops the heart? ?burns the tissue?. Electricity will always take the easiest (most conducting) path, so if it hits the sea, it will travel easily through the conducting salty water and perhaps less easily through the fish and so won’t pass through them. When lightening hits the water a certain amount of energy is dissipated – it will slightly raise the temperature of the water/path it’s taking until all the energy has gone so it can’t zap a whole oceans worth of fish.
      Interesting!

Comments