Recent content by tasnim rahman

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    What is the significance of thermal voltage in semiconductors?

    Thank you for the answer. But I am not quite familiar with bandgap voltage. If you could give a more elaborate description of it or direct me to me a similar link or book, then it would be really helpful. Also, I was looking for the physical significance of the thermal voltage, but didn't...
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    Confusion about transformer and flux

    Thank you very much. I think I get it now. But if there is any other problem I will just post it here. Thanks again.
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    Confusion about transformer and flux

    Thank you, and I think I have already come to that conclusion, in a recent post. That, the back e.m.f. is actually a manifestation of the drop of the supply voltage across the inductor, and as such is equal to the supply voltage, with the current lagging behind the voltage by 90°. But, another...
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    Calculating Tension in a Nonmassless Rope with Unequal Vertical Forces

    The tension of the rope acts inside the rope. If you cut the rope, you will find the tension, acting outwards in either of the cut ends, as seen in the picture. Then, once you know that you can calculate the tension using anyone half of the ropes. In the example, let's say the rope has mass 1...
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    What is the significance of thermal voltage in semiconductors?

    I suddenly came across this thread from a long time ago, while searching on the same topic on the Internet. As I have problem with this topic too, I am posting my question here, instead of on a new thread. I did not quite grasp the explanation above very well. And, I was wondering if it had...
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    Confusion about transformer and flux

    Please. May I have some help here, in clearing this thing out. @sophiecentaur
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    Confusion about transformer and flux

    Sorry everyone, I have been away from this thread for a very long time, what with quizzes and exams being held almost everyday, at the university, and also due to some other circumstances. :frown: Well anyways, I am finally back here, and am surprised that this thread has not been closed yet...
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    Confusion about transformer and flux

    That means that the applied voltage and the back-emf actually cancel each other out. Right? :confused: I am sorry, but I seem unable to grasp the effect of infinite inductance. Does this mean that in an ideal transformer, magnetic flux can be produced from zero current? If so, that seems to...
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    Confusion about transformer and flux

    Thank you for that. But the primary coil behaves like an inductor. And in an inductor, the current lags the voltage by 90°. So, shouldn't the current in the primary lag by 90°?? :tongue:
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    Confusion about transformer and flux

    Lets consider an ideal transformer in no-load state, i.e. with the primary side connected to a voltage source, and the secondary side in open-circuit. Now, this is what I believe; the voltage Vp in the primary produces a current, which lags the voltage by 90°, as would be in an inductor. This...
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    Average value of current from graph.

    I know that much, thank you. The problem is with the "sine wave". If you would read my previous post, the one before the last post, you would see that it is one continuous sine wave, but more like two sine waves joined up. How do I find the average value for that part. @ psparky.
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    Average value of current from graph.

    Could someone kindly help me solve this problem. Its just that I am in a hurry, because I have an exam tomorrow on this.
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    Average value of current from graph.

    I am sorry, but you probably didn't see the "sine wave" thoroughly enough. Yes, it starts and ends at 30, as if representing a cycle. But, if you notice the peaks you will see, one goes from 30 to 40, representing a change of +10, while the other goes from 30 to 10, representing a change of -20...
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    Average value of current from graph.

    This isn't exactly homework, for which I am not posting in the homework section. I am currently doing my undergrads, and am in the second semester of my first year. I am going to give my finals which start from tomorrow, with the first subject being Electrical Circuits II. I was solving the past...
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    Why do attractive force have a negative sign? like F= -GMm/r^2

    Centripetal force is our way of describing a theoretical force that moves an object in a circular path. In reality, this force can be provided any force. For the satellite its the gravitational force; for a coin at rest on a rough circular rotating disc, its the frictional force; for a stone...
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