5H10.20 Oersted's Experiment

PURPOSE: To demonstrate magnetic Fields

DESCRIPTION: An easy-to-see lecture-table compass is placed just beneath a brass bar, which can carry a heavy current. The brass bar is oriented north-south, so when the current is switched on, the compass rotates very conspicuously to an east-west position.

SETUP TIME: Medium

COMPONENT LIST:

    


  1.  Lecture-table compass				??


  2.  Brass bar						??


  3.  Power Supply					Power Supply Area

SUGGESTIONS:

REFERENCES: 2122 4.4; PIRA 5H10.20

OTHER NOTES: In 1807, Hans Christian Oersted announced that he was looiking for a connection between electricity and magnetism - as was all Europe. Years went by and the experiments were all negative. Oersted became convinced that there was no connection. Ironically, he developed a lecture demonstration to "prove" this "fact". He placed a current-carrying wire crossiwse over a compass needle. One day in 1820, at the end of the lecture, he placed the wire parallel to the needle. He was startled to see the needle deflect strongly. He reversed the current, and saw the needle flip over. This is to my knowledge the only physics principle that has ever been discovered durin ga lecture demonstration. By the way, Oersted's contemporaries "reacted violently to his demonstrations in subsequent lectures. The audience 'disliked' the force at right angles...." (Magnets: The Education of a Physicist by Francis Bitter)