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On such diagrams, junctions are usually marked with dots, and they are clearly visible in this case, too. There is no dot at the crossing of two wires just below D. When the switch is open, clearly, there is no flow in this "C-loop", only D and B will light up. When the switch is closed, there will however still be no flow through the C bulb, as there is a ...

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One way to think about it is similar to a chemical equilibrium. Electron-hole pairs are spontaneously generated every now and then from random thermal fluctuations, and when an electron collides with a hole they annihilate with each other (some fraction of the time). The frequency with which electrons and holes collide is $np$. In steady-state, this ...

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"Why is $np$ always equal to $n_i^2$ ?" Well, first of all, the easy way to answer your question "Why is $np$ always equal to $n_i^2$ ?" would be simply to notice that $np$ is independent of the Fermi level $E_F$, and thus independent on the fact that the semiconductor is doped or not. In the case of a non-degenerate semiconductor (i.e. when $E_F$ is ...

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Electrons and holes occupy their states according to the Fermi-Dirac distribution, which has a single parameter $E_f$, the Fermi level (assume a fixed temperature). Provided $E_f$ is in within the band gap and far from the band edges, the (energy integral of) Fermi-Dirac takes an exponential form $\propto e^{E_f}$ for electrons and $\propto e^{-E_f}$ for ...

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In general reducing the voltage to control the rpm of a motor is not a good strategy and it's even worse when executed with resistors. If you use a resistor, the voltage drop on the resistor will be $V_{R}=RI_m$, i.e. the remaining voltage for the motor will be $V_m=V_0-V_R=V_{supply}-RI_m$. The more torque the motor has to generate, the higher the current ...

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Consider shape, capacitance, size , max. voltage/current it can withstand. Try to look at some capacitor, may be from your house fan. (They generally burn after some time.) You will find your answer. Economically, CuriousOne answers correctly.

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Solids are nearly incompressible, so it matters very little if you use the heat capacity at constant pressure or constant volume. How much work do you think an expanding solid sample can do if held at a constant pressure, even if the pressure is high? At constant pressure , $\Delta PV$ is going to be very small, so the change in internal energy will be ...

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What happens when you touch an object with a positively charged object? Ans: It gets positively charged. Now, you have connected a semiconductor to a positive end of battery. What do you expect? Ans: Yes, it gets positively charged. Will the terminal pull electrons out of the doped silicon, or equivalently, inject holes into it? Yes, it will. ...

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