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A DC voltage must have a polarity, however this polarity is always in reference to some common point and has no meaning on its own, the same with voltage. Usually this common point is the circuit ground, which may or may not be earth ground. Example: A household AA battery has a positive and a negative terminal, the positive terminal is +1.5v in relation to the negative terminal, and the negative terminal is -1.5v to the positive terminal.
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What voltage is DC?
A voltage DC(direct current voltage) is a uni-direction steady voltage. It is the opposite of an analog/alternative voltage which varies in polarity and direction with time.
Can you reverse the polarity of AC and DC?
We have the capacity to reverse the polarity of a DC voltage, at least as regards what we apply it to. When we consider a DC motor, like, say, the ones in the little "robot wars" we see on TV, the motors can be run in reverse by reversing the polarity of the applied DC voltage. We normally consider AC as already reversing its polarity. It is, after all, AC, which is alternating current. The current alternates because the voltage alternates. We'll avoid any further discussion of the polarity of AC voltages here and leave it at that.AnswerThe problem, here, is that 'polarity' has several different meanings.Polarity, in the sense of 'electric charge' cannot really be applied to a voltage (potential difference) although it can be to a potential (although the polarity is relative; it depends on the point of reference).Polarity, in the sense of 'direction', can be applied to a voltage. For example, is the voltage acting clockwise or counter clockwise around a circuit?Polarity, in the sense of 'connection', can be applied to a voltage. For example, it's important that the line conductor is connected to the centre terminal of an Edison lamp holder or to one or other of the slots in a receptacle (power socket).
How can the output voltage of a DC generator's polarity be reversed?
The polarity of DC generator can be reversed by reversing the field current as well as direction of rotation
Why are you using DC voltage for pressure test?
There's no such thing as a 'negative voltage' in the 'polarity' sense, only in the 'direction' sense. So what exactly are you asking?
How can calculate resistance for negative dc voltage?
Resistance calculations are the same no matter what the polarity of applied voltage. R=E/I Resistance (in ohms) = Voltage (in volts) divided by Current (in amperes)
What is the function of a dc motor?
Its a motor that will do some work if you feed it some DC voltage. Reversing the dc supply voltage polarity will make it run in a reverse direction. The electric windows in your car is a good example of a DC motor's usefulness. The window up-down switches simply reverses the + and - polarity of the 12 volt vehicle supply to the window motor to make it take the window up or take it down.
How do you energize a furnace relay?
BY applying a voltage to the relay's coil connections. Could be DC or AC at a specific voltage. If it's DC, watch the polarity. If it's AC, polarity doesn't matter. HOWEVER, VOLTAGE DOES MATTER, so don't go applying 120 VAC to a relay when it needs only 16 VAC, and DON"T APPLY AC to a DC relay. Could burn up quite nicely if you're not careful.
When is it important to make sure to match the polarity of the meter leads to the polarity of the circuit being tested?
This is important when meter cannot display negative values, e.g. it is analogous meter with scale. Most digital meters can display negative values. P.S. I am amateur in elecrtonics.
How does clipping circuits work in lab?
A clipping circuit works by the switching action of a diode when it is used in a circuit with a source voltage that changes polarity. In the forward direction, the diode's voltage is added to any dc value that is in series with it. If the source voltage is greater than the dc value at a particular instance, the diode will limit the output to the dc value. Otherwise the output voltage will equal the input voltage.
Does the alternating current supplied to the armature winding of a DC motor gets converted to dc by a commutator before it flows through the armature coil of the DC motor?
The commutator is a rotating switch, which reverse the polarity of the generated voltage every half-cycle. So it acts to rectify the output voltage.
Why freqvency in AC and Why not in DC Voltage?
Frequency with AC is how many times in one second it goes thru a cycle of reversing polarity twice. DC does not reverse, in other words the frequency is zero.
What are AC and DC?
AC and DC are alternating current and direct current, respectively. The two terms generally speak to a voltage source and the way it causes current to flow in a circuit.AC means the applied voltage changes polarity, and, therefore, the current flow in a circuit will change directions in response. The best example is probably the AC power grid, and the grid distributes electric power across a wide area. In the AC power grid, the voltage varies in the form of a sine wave. It varies from zero to a positive peak, back to zero, to a negative peak and back to zero. It actually changes polarity, and this cycle repeats continuously at some rate. The voltage out of the wall socket in a house in the US is AC at 60 Hertz (60 Hz), which is 60 cycles per second.DC means the voltage source has a fixed polarity. Current in a DC circuit will flow in only one direction. The most common example is a battery, and the terminals of this voltage source are positive and negative. The voltage applied to a circuit will result in unidirectional current flow.When we compare DC and AC circuits, we generally consider that in the former, the applied voltage has a fixed polarity and unidirectional current flow. In the latter case, the polarity of the applied voltage changes, and the direction of current flow in an attached circuit will also change.
