In an integrated circuit, the current density in a

In an integrated circuit, the current density in a 2.6-μm-thick × 74-μm-wide gold film is 8.0×105A/m2 .

Here is what I got.

(8.5010^5)(2.610^-67410^-6)= 1.6354*10^-4 μm.

Now I am asked to find how much charge flows through the film in 15 minutes? How do I do that from here and am I doing this right. Appreciate the help

2 Answers

  • Your number is right, but you blew the units. It is actually µA.

    Since 1 amp = 6.24E18 electrons/sec, the charge passing in 15 min (900 sec) is:

    N = 6.24E181.6354E-4900 = 9.184E17 electrons


    0.147 Coulomb

  • Between the question and your answer, the current density has changed from (8.0 10^5 A/m²) to (8.50 10^5 A/m²). Which is it?

    The units in your answer are wrong:

    (A/m²) * (m²) = A {Not μm}

    So your calculation gives you the current flow.

    The other thing that you need to know is that:

    Charge {in coulombs} = Current {in amps} * Time {in seconds}

    15 minutes = (15 * 60) = 900 seconds

    So you just need to multiply the current that you calculate by 900 to get the charge flow in 15 minutes.

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