Hey there! Sign in to join this conversationNew here? Join for free
x Turn on thread page Beta
    • Thread Starter

    Ok so in my lecture notes we are given an example calculating the resistance of the heart and i will literally copy down exactly what's in my notes onto here. I missed that lecture, so i'm a bit confused. for starters, the equation doesn't even equal 25

    Consider the heart in the centre of the thorax

    thorax: phi=30cm (not sure what the symbol phi is)
    resistivity = 2ohm m

    heart: phi=50mm
    resistivity=20ohm m
    potential diff = 5mV

    R = resistivity x L / a =(2 x 100 x 10^-3)/(pi x 0.625 x 10^-3) = 25ohms

    they've used resistivity of the thorax, not the heart then where does 0.625 come from? it's obv in mm

    • Community Assistant

    Community Assistant
    phi is clearly diameter, in case you haven't worked that out.

    They've done resistivity(thorax) x length(heart)/pi (radius(heart)squared)

    Should have given 102.

    Of course, if he had taken the diameter measurement when doing those calculations instead of radius, it would have given 25...

    As to why the resistivity of the thorax has been used, no idea. Does he use the thorax measurements elsewhere? If so maybe its another misprint.
What's the best type of cheese?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.