Turn on thread page Beta
    • Thread Starter
    Offline

    15
    ReputationRep:
    An insulated metal conductor is earthed before a negatively charged object is brought near to it.
    a) Explain why the free electrons in the conductor move as far away from the charged object as they can.
    b) The conductor is then briefly earthed. The charged object is then removed from the vicinity of the conductor. Explain why the conductor is left with an overall positive charge.
    Offline

    11
    ReputationRep:
    This won't be a mark scheme answer but comes from own intuition

    a) Similar charges repel

    b) The electrons have been repelled into earth. There are now more protons than electrons in the conductor, which makes it positively charged.
    • Thread Starter
    Offline

    15
    ReputationRep:
    (Original post by s.xw)
    This won't be a mark scheme answer but comes from own intuition

    a) Similar charges repel

    b) The electrons have been repelled into earth. There are now more protons than electrons in the conductor, which makes it positively charged.
    Could you explain how you came up with that answer for b in detail. Do electrons first flow from the charged object to the metal so it has a negative charge? And then when earthed the electrons flow to the ground?
    Offline

    11
    ReputationRep:
    The way I read it, the charged object is brought near the conductor, but does not touch it. This means that unless there is a spark, the electrons in the negatively charged object do not move.

    Part B is connected to Part A, which gives you a clue. It tells you that electrons in the metal conductor want to move as far as way from the charged object as it possibly can. When the conductor is earthed (briefly) the electrons seize the opportunity to move away into the earth (excuse this unscientific terminology).

    Are you familiar with the concept of earthing?

    Because the conductor was only earthed briefly (key word), when the charged object was removed, electrons were not able to return to the conductor to restore the neutral charge. Hence, it is left with a positive charge.
    Posted on the TSR App. Download from Apple or Google Play
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: October 25, 2017

University open days

  • University of Warwick
    Undergraduate Open Days Undergraduate
    Sat, 20 Oct '18
  • University of Sheffield
    Undergraduate Open Days Undergraduate
    Sat, 20 Oct '18
  • Edge Hill University
    Faculty of Health and Social Care Undergraduate
    Sat, 20 Oct '18
Poll
Who is most responsible for your success at university

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