# Tag Info

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A current source is a complex (and probably non-existent) power supply with internal resistance which can adjust its terminal voltage (or resistance) so that the current flowing through it is always at a predetermined level.

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Yes. The name is “current source.” Since you say the video already mentions this, I am not entirely certain what you’re looking for here.

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Perhaps it is best explained on a simple example: Say you want to manufacture a simple electric radiator: The tension (voltage) of the network is a given constant,say $Vo = 220 V$. (of course it is AC, but this value is just an average) You know that for heating a given room you will need say $1kW$ ($1000$ Watts) of power. What resistance will provide you ...

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I am sure all the other answers are excellent, providing varying degrees of details of all the physics involved. If anyone wants a more naive but perhaps more intuitive explanation, here's my two cents. First off, let's not think of an electrical device as a collection of discrete parts (ICs, capacitors, inductors, resistors, etc.), but instead, as a black ...

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It can all be explained by the resistance of the involved parts. How does a home appliance limit the amount of current that flows through it? It limits the current by behaving like a resistor Are there some resistors set up in series in order to cut down the current flow before it actually reaches the device? The relevant resistor is the device itself, ...

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Voltage, current, and resistance are in a relationship: $V=IR$. This isn't to say that one "causes" the other. We don't always say that voltage "causes" resistance. It's just a relationship that's due to the laws of physics. If you change one variable in that equation, one or another must change. Now, in the cases you are interested ...

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Potentiometer wire has high resistance relative to what? If it was meant that relative to conducting wires, it must be high then thats because, in a potentiometer you just connect a wire to a voltage source $V$. A low resitance wire provides no load and would drive huge currents without a limiting resistance in the circuit. wont the current skip ...

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Potentiometer wire has high resistance so that by turning the control knob to "add" more wire in series, the measured resistance increases by a convenient amount. If the "pot" were wound instead with copper wire, which has very low resistance, it would take a huge increase in the number of wraps in the pot to get a measurable increase in ...

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Your house knows nothing. ((Jon Snow)) But the appliances builders know something: They know the voltage of your outlet They know how to build a transformer They remember well Ohm's law: $I=V/R$ Since they know the voltage of your outlet they can equip the appliance with the right transformer, to get the voltage output of their choice; and of course they ...

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A toaster limits the amount of current flowing through it via its resistive elements which convert everything to heat. A transformer connected to AC power mains limits the amount of current flowing through its primary windings via inductance: inductance is a form of opposition to the flow of AC. Even though the windings consist of copper wire that has low DC ...

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I've +1'd @gandalf61's answer for using the term "constant voltage" which is an important electrical concept, and the rest of that answer is spot on too. I would add that two different concepts are often discussed using the same word, "limited". In normal operation, the current that an appliance will allow to flow is limited by its ...

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How does the electric circuit in our home „know” how much power to deliver to each socket? It doesn't. It will supply as much as the appliance demands, up to a point. How does a home appliance limit the amount of current that flows through it? It depends on the appliance. The simplest type is pure resistive, like a kettle or toaster. The resistance of the ...

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To very briefly summarize the other answers: A power source is characterized by its voltage only. A power consumer is characterized by its resistance only. The combination of the two determines what the current will be (Ohm’s law: $I=\frac{U}{R}$). If the resulting current is too much, bad things will happen. At best, an overcurrent protection device will ...

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The appliances uses the electrical energy to get some useful effect. Sometimes it means high currents, as for an electric shower. For a voltage of 127 V, it can work with a current of 40 A, which requires thick wires between the fuses and the shower. There are industrial devices that needs much higher currents (big motors, electric arc furnaces for example), ...

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How does a home appliance limit the amount of current that flows through it? Strictly speaking, the way an appliance limits the current flowing through it is usually with a fuse, either a replaceable one or a part of it's circuit board which will melt if too much current passes through it. Electronic devices and appliances are designed to draw only a ...

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There is already a good answer here, but I would like to add that a so-called "15A socket" is not so called because it "contains" 15A. The power grid and the wiring in your walls are capable of delivering hundreds or thousands of Amperes to any socket in your home. At least, it could do so for a brief interval before the smaller wires ...

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Your home circuit does not "know" how much current to deliver to each socket or appliance. The circuit supplies a constant voltage, and it is then up to each appliance to limit the current that it draws. Some simple appliances, such as lights with old incandescent bulbs or electric toasters or irons, are basically just a resistor (possible a ...

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Electric supplies to homes and industries are standardized in countries. This allows devices which are used in homes or in factories to be accordingly designed. For e.g. if the standard single phase RMS AC supply voltage is $240$ V, appliances would be designed such that they operate without electrical failure at that input voltage. What I mean by this is ...

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Dynamic resistance is defined as the differentiation of the voltage with respect to the current in a VI curve at the operating point. It is an interesting phenomenon that the dynamic resistance is the resistance that the AC voltage sees, since dynamic resistance, $r=\frac{\Delta V}{\Delta I}$ and the AC voltage is the voltage that is changing. To speak more ...

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To enlarge slightly upon DKNguyen's answer: Indeed, the thing that causes air to break down is the strength of the electric field in the gap between the switch terminals, as measured in volts per meter. For small values of the gap, even a small number of volts will produce a strong field. Furthermore, if there are any sharp points or asperities on the ...

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I assume you're asking about a mechanical switch and not a solid-state switch. Yes, there is a spark when you flip a mechanical switch closed because doesn't just close cleanly. It closes, then bounces open, then closed, then bounces open, etc. until it finally stays closed. The voltage producing the arc is not the voltage from the supply. It is the voltage ...

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As @chemomechanics suggests, the Laplace transform approach would be a good choice to find a close form solution. First, transform your time-domain (t) circuit to frequency-domain (s) and then solve it with any/all of the normal electrical circuit solution techniques. Below are the fundamental element models in Laplace. In your case, you have no initial ...

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First, note that your circuit diagram shows the flow of conventional current which can be very confusing to a student trying to understand the operation of a diode, never mind a transistor. Reversing the arrows of your diagram to show electron flow shows more clearly the physics of what's going on: Electrons flow from the connected negative battery terminal ...

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Issue#1. There are various aspects to consider here, let me skip for a moment. Issue#2. Ok, I think I see what your instructor means but it might be indeed a bit confusing. First of all: outside the depleted region at the EB and BC junctions, in the non-depleted portion of the base (I don't see it in you sketch but it is there, at least in normal conditions)...

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The emitter is very heavily doped, and the base is very, very thin and very lightly doped. The collector is moderately doped. Typically the emitter is the most heavily doped, the collector is the most lightly doped, and the base is somewhere in the middle. current doesn't move by means of recombination of electrons and holes! Current moves by means of flow ...

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With the given electric field $$\vec E=(10 \hat{\mathbf a}_y + 5 \hat{\mathbf a}_z) \cos (\omega t + 2y - 4z ) \rm{\ V/m},$$ what is the propagation vector $\vec k$ in ($\vec k\cdot \vec r$) ? With that $\vec k$, what is the value of $\vec k \cdot \vec E$?

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