Alternating current, direct current & what is frequency? | Physics | Khan Academy
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- Опубліковано 19 бер 2020
- Current that keeps changing is direction is called alternating current, (AC) whereas the one that never changes its direction is called direct current (DC). Power can be transmitted with low heating losses in the form of AC (not DC). The frequency of the AC in India is 50 Hz. This means the current changes it's direction 100 times per second.
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Answers:
1.
DC - Direct current
AC - Alternating current
2. If the frequency is 50 Hz it means that there are 50 cycles in a current per second. Also, it means that the current changes it's direction 100 times a second (a cycle consists of the change of direction twice)
3. Sending a large amount of voltage through long distances is uneconomical thus a better way to reduce the cost us to send much lower voltage through the same distance and then increase the voltage through a transformation when it reaches its required location. Now, since the transformer only works if the current is alternating, the current reaching our homes is AC.
Feel free to correct my mistakes if any
Transformer can be either step-up or step down. Especially in India, Transformers that we find near our home is step down. It converts high voltage ( usually 11 KV or 1100 Volts ) to low (415 volts). From the transformer three phase lines and one neutral is supplied to electric lines posts. Form that , one phase line and neutral line gives us normal 230 volts .
@Jo Hello
In ac current goes backwards and then foreword
When it goes backward or forward does it cover the whole circuit once
Or from some distance it come forward again
@@faxedits8The charges may not cover the whole circuit when it goes forward or backward.
When the charges flow from one point to another, they will continuously change their direction in a to and fro manner and reach the final destination .
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I believe another reason why high voltage / low current A.C is used in power lines is for cost reasons, so that thinner electrical cables (i.e. less copper) can be used.
Yeah, cause less energy is lost. There isn't as large a need to reduce resistance
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If AC current “flows” in both directions, why is there a need to distinguish a live from a neutral wire?
The potential difference of the neutral is always kept very low(almost equal to zero).
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Sir , one question that troubles a lot of people , if current alternates why do we distinguish the 2 cables (for a single phase ) as hot wire and neutral . if it alternates then shouldn't for the first half cycle the brown wire (L) to be the hot one and blue wire (N) to be the neutral and for the second half cycle the brown wire to be the neutral one and blue wire to be the hot one ?
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Current come in 2 flavours 😁0:38
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Sir in AC if current goes back and forth how will the destination be reached
Electrons go back and forth in the entire circuit...so the electrons also move inside the electrical components coz it's also a part of the circuit...i think so... I'm not sure...but i my teacher answered me that it's electrical energy which reaches the destination...
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What will happen if the current is too high??
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..in my country we have 50hz...if we do not apply a bridge rectifier after the step down transformer for T8 LED tube..does it save more energy since we can't notice 50hz flickers ?..and does it prolong the LED tube lifespan..?
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can the magnitude of dc current change?
Sir, if AC is the current driving behind tube lights and other devices, then why do fans rotate in one direction only, fans also receive AC, then fans should rotate in one direction and then in another direction, for a fan to rotate AC has to be converted in DC via rectifier, so my question is rectifier not used in powering tubelights ?