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Electron beam question

  1. Mar 7, 2010 #1
    1. The electron beam inside a television picture tube is 0.300 mm in diameter and carries a current of 52.0 mu A . This electron beam impinges on the inside of the picture tube screen.

    a)How many electrons strike the screen each second?

    b)What is the current density in the electron beam?

    c)The electrons move with a velocity of 4.50*10^7 m/s . What electric field strength is needed to accelerate electrons from rest to this velocity in a distance of 5.70 mm?

    d)Each electron transfers its kinetic energy to the picture tube screen upon impact. What is the power delivered to the screen by the electron beam?

    Any help will be appreciated :smile:

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Mar 7, 2010 #2


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    Homework Helper

    what are the UNITS of current [that is, what's an Ampere] ?
    what is current MADE of ?
    go back to the chapter on fluid flow, look for density times velocity times Area ...
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