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Homework Help: X-rays and their wavelengths

  1. Feb 7, 2006 #1
    X-ray tubes used by dentists can have voltages as high as 80kV to accelerate the elecrons to produce the X-rays. What is the most lowest wavelength that can be produced by such electons?

    This problem seems almost too easy... i need a check

    [tex]\lamba = \frac{1.24x10^3 V^{-1} nm}{80kV}[/tex]

    [tex]\lamba = 0.0155 nm[/tex]
  2. jcsd
  3. Feb 8, 2006 #2


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    Check the units in your expression.
  4. Feb 8, 2006 #3
    i thought wavelengths were in nm? why do I get units of nm/v^2?
  5. Feb 8, 2006 #4
    the numerator should be 1240eVnm
  6. Feb 8, 2006 #5
    I am stil getting [tex]\lambda = 0.0155 nm[/tex]

    I used the formula [tex]\lambda=\frac{h*c}{80kV*e}[/tex]

    and I got the same results. am I doing this correctly?
  7. Feb 8, 2006 #6
    what Tide said. Look at your units. Carefully.
  8. Feb 8, 2006 #7
    ignoring the first part, and using:


    should it be in units of (eV*s)/V ?? shouldnt it be in meters?
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