Recent content by NanoChrisK

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    Fermi Energy in Intrinsic Si, Ge, and GaAs

    Looking at the question more closely, I noticed it asks for the Fermi energy "with respect to the middle of the bandgap (Eg/2)." Does this mean that I can just ignore the Ev + (1/2)Eg - (3/4)kT part of the equation? I think this is the solution.
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    Fermi Energy in Intrinsic Si, Ge, and GaAs

    Homework Statement Using the values of the density of states effective masses me* and mh* in table 5.1, find the position of the Fermi energy in intrinsic Si, Ge, and GaAs with respect to the middle of the bandgap (Eg/2). Table 5.1 shows the following density of states effective masses me*/me...
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    Why does [sin(θ/2)-cos(θ/2)]^2 not always equal 1?

    Yes, I understand now :D There should have been a -2AB in the middle there. Thanks for making that clear to me!
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    Why does [sin(θ/2)-cos(θ/2)]^2 not always equal 1?

    Ok I see what I said previously was incorrect! Because (A-B)2 = (A-B)(A-B) = A2 - 2AB + (-B)2 = A2 - 2AB + B2 NOT what I had earlier. I guess I just need to re-take basic algebra! Thanks Mark!
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    Why does [sin(θ/2)-cos(θ/2)]^2 not always equal 1?

    Hmm I may be wrong, but I think you meant to type "(A -B)2 ≠ A2+A2" (with a + in the second half of the equation) This is the form I gave it in, unless I'm missing something. Is this not correct? I'm getting this from: (A-B)2 = (A-B)(A-B) = A2 + AB - AB + (-B)2 = A2 + B2
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    Why does [sin(θ/2)-cos(θ/2)]^2 not always equal 1?

    Homework Statement Does [sin(θ/2)-cos(θ/2)]^2 equal 1 for all values of θ? I need to figure this out to solve a physics problem. Homework Equations sin^2(A)+cos^2(A)=1 The Attempt at a Solution [sin(θ/2)-cos(θ/2)]^2 =sin^2(θ/2)+cos^2(θ/2) =1 But this isn't what I get when I put...
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    Finding |<+y|-θ>|^2 in terms of θ

    Homework Statement What is the probability that an electron emerging from the plus channel of the first device will end up in the minus channel of the second device? Express your answer in terms of θ. (Refer to the attached image) Homework Equations This uses the outcome probability rule that...
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    Is a vacuum balloon posible? Theoretical material?

    Homework Statement So, I was sitting in my algebra based college physics class and we were talking about buoyancy. According to Archimedes' Principal, "an object that is completely or partially submerged in a fluid experiences and upward force equal to the weight of the fluid displaced."...
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    Solving a Tricky Pulley Problem: Input Forces for 200 N Load

    Thanks a lot! I would not have been able to figure that out without your help!
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    Solving a Tricky Pulley Problem: Input Forces for 200 N Load

    Correction: substituted wrong tension. T1 = Fi, so solving for T1, Fi = 50 N
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    Solving a Tricky Pulley Problem: Input Forces for 200 N Load

    Ok I think I got it now. I just set up equations for both of the pulleys and substituted the T2 from the second equation for the 2T1 in the first equation. That way I could solve for T1, which also equals the force required for equilibrium. Am I on track here?
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    Solving a Tricky Pulley Problem: Input Forces for 200 N Load

    I'm just a bit lost on the setting up the equations. I know, for example, that if you just had 1 stationary pulley attached to the ceiling, you are just changing the direction of the force, so the ideal mechanical advantage is 1, giving the equation: Ideal Mechanical Advantage = Force out /...
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    Solving a Tricky Pulley Problem: Input Forces for 200 N Load

    Yes, but wouldn't the tension be equally distributed among the 3 lengths of cable supporting the weight bearing pulley? That would give it an ideal mechanical advantage of 3, would it not? Or are you saying that for mechanical advantage, I only have to take the tension of the two lengths of...
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    Solving a Tricky Pulley Problem: Input Forces for 200 N Load

    Homework Statement "What are the input forces needed to lift the 200 N load for the arrangement shown?" Notice how there are two movable pulleys that move in opposite directions as the weight is lifted. That is the confusing part to me. Homework Equations Ma=Fo/Fi The Attempt at...
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