Why is current a schalar quantity?
475038
A current can only occur along a potential difference. Any vectorial information is included in that potential difference, the current just is the amount of charges exchanged along that potential difference over time.
1055209
The top answer is incorrect.  In both cases, the current woul go on infiniitely, because energy will keep on traveling, but the current will get weaker and weaker, because it will keep spreading aparty, until the ammount of current in negligeble.\n\nHope this helps.
1050520
Think about the simpliest capacitor. It is clear that two metal plates that don't touch won't let a DC current pass, right? But the spacing is very thin so that the plate's charges can effect one another. When you first put current (even DC) to a discharged capacitor, it charges up and for a brief time it does conduct current. How long? Well it will charge to 2/3 of the total voltage in RC seconds (where R is the resistance of the circuit). So when AC current is "fast" enough, the cap is constantly in a charge/discharge state and current flows. The effective resistance (reactance) of the cap is 1/(2*pi*F*C). So the resistance goes down as the capacitance and the frequency rises.\n\nThe inductor, on the other hand is just a coil of wire. Again, it is easy to imagine that it will conduct DC. But when you first apply current (even DC) to a coil, the magnetic field will interact with the coil and produce an opposing voltage. This only occurs when the magnetic field is forming or collapsing (remember, magnetic fields that do not move do not produce electricity). So right when you change the current, the inductor will "resist" the change, but if the current doesn't change, it is just a wire. The reactance of a coil is 2*pi*F*L, so the resistance increases with frequency and inductance.\n\nNow, combining inductors and capacitors is another interesting subject, but you didn't ask about that....
698625
Maybe because it is depicting Current flow NOT Electron flow??
232108
Ideally a capacitor has an infinite resistance (which is a DC measurement). However the AC equivalent of resistance, reactance (usually denoted as X), tells you how much AC current a capacitance passes with a given AC voltage applied across its terminals. Reactance depends on the AC frequency. It is X = 1/(C*W), where C is capacitance and W (omega) is 2*pi*frequency. Similarly to Ohm's law, you can find average current from E = I*X. Unlike Ohm's law, this is true for average current but not for instantaneous current, since E and I are 90 degrees out of phase.
244997
An operational amplyfier has a gain of one.Thetrefore it is very ussefull in logic circuitry.
266980
4. The current does not change.  I=E/R so multiplying the numerator and denominator by 0.50 results in the same answer, does it not?
461173
Maybe in mathematics sqrt of -1 = i, but in electrical engineering it is j.\nIn electrical engineering and related fields, the imaginary unit is often written as j to avoid confusion with a changing current, traditionally denoted by i.\n\nThis represents the imaginary component of electronics which cannot be ignored. Phasor diagrams may help to explain this phenomenon. A phasor is a constant complex number representing the complex amplitude (magnitude and phase) of a sinusoidal function of time. It is usually expressed in exponential form. Phasors are used in engineering to simplify computations involving sinusoids, where they can often reduce a differential equation problem to an algebraic one.
944873
Charge is difficult to explain without just saying how it interacts with other charge...\nBasically its a fundamental property of matter, like mass. The difference is, since charge comes in two types, positive and negative, in most large collections of matter, they cancel out and things are generally electrically neutral (have no charge). It responds to other charges through electromagnetism, much like masses affect each other through gravity, and is affected by electromagnetic fields created by currents, and magnetic fields also.\n\nCharge sits on a fundamental particle, or atom, or molecule, or larger particle. If that particle is in a collection of other particles, all of which are moving in the same direction, you have a current - a flow of charge. An ampére (or amp) is a unit meaning "one coloumb per second", or that at a point in a circuit where 1 amp is flowing, one coulomb of (positive) charge is passing per second. The coulomb is actually defined in terms of the ampere - it is the amount of charge that flows past a point in one second when the current is one amp.\n\nIn the example you've given, 240 C passes a point every five minutes, or every 300 seconds. So every second, (240/300) C/sec flows. This is the same as saying that 0.8 (=240/300) amps is "flowing" at that point. The matter is complicated by saying that current flows - it doesn't really, its a property of a stationary point in a circuit. The charge flows. If the rate of charge flow changes, so will the current, but saying that the current flows is a bit of a misnomer. But we're stuck with it.\n\nHope this helps.
60608
electricity (î-lèk-trîs´e-tê), class of phenomena arising from the existence of CHARGE. According to modern theory, most ELEMENTARY PARTICLES of matter possess charge, either positive or negative. Two particles of like charge, both positive or both negative, repel each other; two particles of unlike charge are attracted. The electric FORCE between two charged particles is much greater than the gravitational force between the particles. Many of the bulk properties of matter are ultimately due to the electric forces among the particles of which the substance is composed. Materials differ in their ability to allow charge toflow through them. Those that allow charge to pass easily are conductors,  whereas those that allow extremely little charge to pass through are called insulators,  or DIELECTRICS. A third class of materials, called SEMICONDUCTORS, is intermediate. Electrostatics is the study of charges, or charged bodies, at rest. When positive or negative charge builds up in fixed positions on objects, certain phenomena can be observed that are collectively referred to as static electricity. The charge can be built by rubbing certain objects together, such as silk and glass or rubber and fur; the friction between these objects causes ELECTRONS to transfer from one to another with the result that the object losing electrons acquires a positive charge and the object gaining electrons acquires a negative charge. Electrodynamics is the study of charges in motion. A flow of electric charge constitutes an electric current. In order for a current to exist in a conductor, there must be an ELECTROMOTIVE FORCE (emf), or POTENTIAL difference, between the conductor's ends. An electric CELL, a PHOTOVOLTAIC CELL, and a GENERATOR are all sources of emf. An emf source with an external conductor connected from one of the source's two terminals to the other constitutes an ELECTRIC CIRCUIT. Direct current (DC) is a flow of current in one direction at a constant rate. Alternating current (AC) is a current flow that increases in magnitude from zero to a maximum, decreases back to zero, increases to a maximum in the opposite direction, decreases to zero, and then repeats this process periodically. The number of repetitions of the cycle occurring each second is defined as the frequency, which is expressed in HERTZ (Hz). The frequency of ordinary household current in the U.S. is 60 cycles per sec (60 Hz), and electric devices must be designed to operate at this frequency. In a solid, the current consists not of a few electrons moving rapidly but of many electrons moving slowly; although this drift of electrons is slow, the impulse that causes it moves through the circuit, when the circuit is completed, at nearly the speed oflight. The movement of electrons in a current is not steady; each electron moves in a series of stops and starts. In a direct current, the electrons are spread evenly through the conductor; in an alternating current, the electrons tend to congregate along the conductor surface. In liquids, gases, and semiconductors, current carriers may be positively or negatively charged.
912980
it depends on the load and the nature of the large appliance\nthe flush example was great but it does not describe dthe momenteraly effect ( it was nice though).\n\nwhen you deal with inductive loads there is something that is called start up current.  it can be 2 to 6 times the nominal current under normal operation. that means that if a device needs 2 amperes of current when it is originally powered the consumption may reach till 10A. then the current returns to normal copnditions. \nall due to inductive and self inductive effects where the device opposes to the change and so on till an equilibrium is reached.\n\nthe demand of the current during start up is great and that is way momentarely  the lghts dim.
814978
The resistance of the filament will increase as it heats up. So you're going to get something called a "transient", which is when the initial value will stabilize (to the working current in this case), after a period of time.\nA lower starting resistance equals a higher starting current.
1115026
Voltage is simply the potential electrical "pressure" of a circuit.  Current is the actual flow of electrons, so that's what's felt.  Think of it in terms of water & pipes.  You feel the water flow, not the potential pressure behind it.  If there is more resistance (smaller pipes, more valves), the potential pressure of the water doesn't change, but the flow is reduced.
94961
Well, not everything obeys Ohm's Law (for example, diodes), so it's not really a law.  It is more of a definition of R (resistance) in the sense that IF a system obeys E = I/R then that system has a well-defined resistance, R.
601069
what is the current rate?
936402
International Standard IEC 60898-1 and European Standard EN 60898-1 define the rated current In of a circuit breaker for household applications as the current that the breaker is designed to carry continuously (at an ambient air temperature of 30 °C). The commonly-available preferred values for the rated current are 6 A, 10 A, 13 A, 16 A, 20 A, 25 A, 32 A, 40 A, 50 A, 63 A, 80 A and 100 A (Renard series, slightly modified to include current limit of British BS 1363 sockets). The circuit breaker is labeled with the rated current in ampere, but without the unit symbol "A". Instead, the ampere figure is preceded by a letter "B", "C" or "D" that indicates the instantaneous tripping current, that is the minimum value of current that causes the circuit-breaker to trip without intentional time delay (i.e., in less than 100 ms):\n\nType Instantaneous tripping current\nB above 3In up to and including 5In\nC above 5In up to and including 10In\nD above 10In up to and including 20In
171066
An electric current is the amount of charge flowing through a fixed position over a period of time. Current is measured in amperes, charge in coulombs, and time in seconds. So an ampere is the amount of coulombs (charge) that flow through a region in one second.\n\nPositive charged particles (protons) don't move; they stay is the atom's nucleus. Negative charged particles (electrons) surround the atom's nucleus and are free to move from atom to atom.\n\nSo more specifically current is the flow of positive charge. This means that the flow of current is in the opposite direction as the flow of electrons. Or current is the rate at which electrons flow out of a region.