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Homework Help: Electroreception, Electric field and charges

  1. Apr 23, 2016 #1
    Hi guys. This is my question. I just wondering what equation that i'm suppose to use.
    1. The problem statement, all variables and given/known data
    What is the maximum distance at which a shark can detect the electric signal emitted by the trout’s heart if the predator is at a point on an axis passing through the centre of the heart? Assume the axis is parallel to the x-axis.
    Figure 6: Electrical potential difference measured at Points A and B by the sensors shown in Figure 7. This is the beating of a brook trout’s heart recorded when the trout is in the position shown in Figure 7.

    Figure 7: Scale drawing of trout seen from above in the aquarium when the measurement is taken by the electrocardiograph. The positions of sensors A and B and the electric dipole representing the heart are all shown.
    sensitivity threshold of the shark is up to 0.5 μV/m

    2. Relevant equations
    E=ke(q/r^2) (the only equation that I can relate to)

    3. The attempt at a solution
    This question is an assumption type question. If any of you guys know how to solve this or just any equation involve is a big help. I tried to read the theoretical part but still it confusing. i tried to use the above equation but i don't actually know how to find the charge of the dipole from the picture. Beside that, I'm wondering if the shark sensitivity is related to the distance or not.
  2. jcsd
  3. Apr 23, 2016 #2

    Simon Bridge

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    Science Advisor
    Homework Helper

    That is correct: therefore there are many ways to go about answering the question.
    The point of this sort of question is to test your understanding and your ability to make decisions. That makes it difficult to help you without doing the problem for you.

    So start by writing down what factors are likely, in your opinion, to affect whether or not the shark can detect the trout?
    It may help you to realise there is a special name for the situation there are two charges close together as shown in the diagram.
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