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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.
Answer
The 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).
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How is a DC permanent-magnet motor reversed?
Reverse the polarity of armature windings of the motor.
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.
What happen if all the diode in bridge rectifier is reversed?
it will work as a rectifier . because the AC current to be rectified will not be effected by this change. the out put DC polarity will be changed.
Is the LM3914 IC protected against reverse polarity?
i would never naturally assume any circuitry to be "reverse polarity" by default even if they are. since this can fry a lot of IC, and micro controllers. there are several options to adding a reverse polarity protection circuit to your project you can find three easy to implement circuits here: http://provideyourown.com/2012/reverse-polarity-protection-circuits/
What is the output voltage of megger is it ac or DC?
megger are available in ac &dc
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.
How do appliances work if AC reverses direction?
AC current alternates polarity back-and-forth continually, by definition. Therefore, it is not possible to reverse AC direction. It is DC current that is directional such that when it's polarity is reversed the motor responds by turning in the opposite direction.
What happens if you reverse DC polarity of a lamp?
nothing
What is the sign for ac and DC current?
AC means alternating current DC means direct current there is no polarity reversal
Why is dc welding develop?
we will have straight polarity and reverse polarity,we can produce the weld with good quality
How do you select polarity doing E6013?
You can weld with E6013 using any polarity. Use DC - or AC for thin sheet metal. Use AC if you have arc blow problems. DC - has the lowest penetration DC + has the most penetration AC splits the difference
How does current flow in a nonreversing motor?
If you are talking polarity. DC motors automotive application run poss to neg. But any dc motor can reverse by changing polarity.
How do you reverse polarity on ac motor?
Reversing polarity is not possible with an ac motor. Some do have wiring that will allow you to change rotation. The type and model of the motor can tell you if it is reversible.
What happens if you reverse a diode in a half-wave rectifier?
you will get the opposite polarity DC as before
How is a DC permanent-magnet motor reversed?
Reverse the polarity of armature windings of the motor.
Does all electronic equipment operate okay with reverse polarity?
If you are talking about AC (ie something you plug into the mains), then yes, because it has no polarity. But there may be safety issues, because equipment is fused on the 'live' side. If you are talking about DC, absolutely not. Semiconductors usually only conduct in one direction, so they can't be reversed. Most electronic equipment works on DC even though it is plugged into AC. The alternating current is 'rectified' into direct current, and the polarity of this will always be correct, however the AC supply is connected.
Can we use DC motor at home?
It would depend on what you are using. A direct current motor has a negative and positive terminals. If connected with the wrong polarity - red on black, black on red it will go into reverse possibly causing damage. Car batteries are used as dc. A lot of small appliances may be dc. Best to check the item you are using and connect the right polarity whether it's AC or DC.
