Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    Name or NavList Code:
    Email:
       
    Reply
    Re: Artificial Horizon.
    From: Geoffrey Kolbe
    Date: 2002 Apr 2, 07:41 +0100

    At 13:30 01/04/02 -0500, you wrote:
    >
    >Geoffrey-
    > field of a small rare earth magnet fixed to the sextant frame, and so
    >damped the movement.>
    >
    > Am I the only one here to wonder how this worked? Copper is non-magnetic,
    regardless of the magnet you used a simple copper strip would not be
    affected by it.
    >
    As the copper strip moves through the magnetic field, electric currents are
    induced to flow in the copper. These electric currents form magnetic fields
    of their own such that they oppose the magnetic field from the magnet,  so
    acting as a brake on the movement of copper strip through the field of the
    magnet. Copper is used because it has very low resistance and so this
    phenomenon is more efficient in copper. This is basically how electric
    dynamos work. Delicate scales are often damped in this way as when the
    scales are steady, the magnet has no effect on the scales at all.
    
    A dramatic demonstration of this effect is to place a block of firewood
    between the poles of powerful electromagnet and then try and split the log
    with a chopper. The harder you try, the further you have to go into the
    bushes to find the chopper!
    
    Geoffrey Kolbe.
    
    
    Border Barrels Ltd., Newcastleton, Roxburghshire, TD9 0SN, Scotland.
    Tel. +44 (0)13873 76253 Fax. +44 (0)13873 76214.
    
    
    

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Get a NavList ID Code

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

    Enter the email address associated with your NavList messages. Your NavList code will be emailed to you immediately.
    Email:

    Email Settings

    NavList ID Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site