Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Drift Velocity

  1. Mar 28, 2012 #1
    Hello experts!

    Higher the emf of the battery implies that the higher the drift speed of the electrons or increase the flow time of electrons from the conductor?

    Which one is true and how??
     
  2. jcsd
  3. Mar 28, 2012 #2

    Philip Wood

    User Avatar
    Gold Member

    Higher emf implies higher electric field strength in the wires of the circuit, so greater force on the free electrons urging them through the wires. So they will reach a higher mean drift speed (at which resistive collision forces balance the electric field forces). Can't, I'm afraid, understand your alternative, but I suspect that it's incorrect.

    Hope this outline explanation helps.
     
  4. Mar 28, 2012 #3
    I mean,
    let a battery of 9volt is connected to the toy fan and on the other hand a battery of 1.5volt is connected to the toy fan.

    So which fan will move faster?

    Will higher emf cause the speed of fan to increase or increase the moving time of the toy fan?
     
  5. Mar 28, 2012 #4

    Philip Wood

    User Avatar
    Gold Member

    The fan will turn faster on the 9V battery (or its motor will burn out!). [Can't see any mention of a fan in your first post...]
     
  6. Mar 29, 2012 #5
    But how will you justify this statement from practical point of view?
     
  7. Mar 29, 2012 #6

    Philip Wood

    User Avatar
    Gold Member

    I won't. I'll leave it to cleverer people – those, for example, who can interpret what you mean by 'a practical point of view'.
     
  8. Mar 29, 2012 #7
    I mean If someone asks you that on 9volt battery fan move faster than on 1.5volt battery, why? then what will be your answer?

    Either more electrons move from 9volt battery to fan than 1.5volt battery or some else reason you would give in justification for your answer?
     
  9. Mar 29, 2012 #8

    Philip Wood

    User Avatar
    Gold Member

    The rate at which electrons flow round the circuit – your "from ... to" is a bit misleading – is increased (for reasons sketched in my first reply on this thread). So a larger current flows through the coils of the motor in the fan, so these (sitting as they are in a magnetic field) experience a greater torque, and the motor runs faster (until this electromagnetic torque is balanced by that from resistive forces).

    Is this the sort of explanation you're looking for?
     
  10. Mar 30, 2012 #9
    Yeah.. Thanks a lot. Thread is solved now. :)
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Drift Velocity
  1. Drift velocity (Replies: 2)

Loading...