Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    6
    ReputationRep:
    Hey! im attempting some of the "harder" questions my teacher has set for me. i have done all but one and this one has completely stumped me. im wondering if someone could point me in the right direction.

    Question:

    "A hollow sphere made of graphite (ρ=25×10-5Ωm) has an outside radius of 100mm and an inside radius of 99mm

    Calculate a rough value for the resistance of this sphere when connected at opposite poles."
    Online

    19
    ReputationRep:
    I take it you're OK with integration between limits.

    Seems the question is badly formed at the moment - seems the obvious thing would be to assume point contact at each pole, but a point has no area and therefore infinite resistance. if you assume a very small contact area then the resistance you calculate is going to be very sensitive to the size of the area you choose so you won't get an answer near your teachers unless you make the same assumption.

    I can't think of a way around it - doesn't seem to be answerable unless a contact area is given.

    very possibly someone else here or on the maths forum knows some super slick trick that I don't
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    What newspaper do you read/prefer?
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • 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

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