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An AM station is broadcasting a radio wave whose frequency is 1400 kHz.

  1. Jun 21, 2010 #1
    1. The problem statement, all variables and given/known data
    An AM station is broadcasting a radio wave whose frequency is 1400 kHz. The value of the capacitance in Figure 24.5 is 8.4 X10 -11 F. The Value of the capacitance in Figure 24.4 is 8.4X10-11 F. What must be the value of the inductance in order that this station can be tuned in the radio?


    2. Relevant equations
    c = f(wavelength)
    S = cu

    3. The attempt at a solution
    but i'm not sure the fomula and i don't know how to get it
     
  2. jcsd
  3. Jun 21, 2010 #2
    What is the natural frequency of an LC circuit oscillation?
     
  4. Jun 21, 2010 #3
    f=1400 Khz
    w= 2*pi*f

    The natural frequency of an LC circuit is w=(L*C)^(1/2);
    solving for L and plugging in the values L=1.5385*10^-10 Henries
     
  5. Jun 21, 2010 #4

    vk6kro

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    Science Advisor

    There is a simple formula for use at radio frequencies, that uses realistic component values.

    It is

    L = 25330.3 / (F * F * C)

    where L is in uH
    C is in pF
    F is in MHz

    8.4 X10 -11 F is 84 pF
    1400 KHz is 1.4 MHz
     
  6. Jun 21, 2010 #5

    vk6kro

    User Avatar
    Science Advisor

    There is a simple formula for use at radio frequencies, that uses realistic component values.

    It is

    L = 25330.3 / (F * F * C)

    where L is in uH
    C is in pF
    F is in MHz

    8.4 X10 -11 F is 84 pF
    1400 KHz is 1.4 MHz
     
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