Alternating current versus direct current

In summary: Google is your friend - but don't rely on it exclusively. You should also read books and learn from people who have more experience. If you keep posting questions that are basic concepts that most people would know, people will not be interested in helping you.
  • #1
halfANDhalf
13
0
i am currently going over ac and dc currents in school but i want to know more but my teacher isn't going very deep into this subject. Can you help me out please?
 
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  • #2
Try using Google for the basics, then re-post if you don't get the help that you want. This stuff is pretty basic, and it would take a WHOLE lot writing to explain it all, especially since you haven't been very specific about what you need to know.
 
  • #3
well what i want to know is what appliances use ac and dc and how they are generated
 
  • #4
You are asking a very trivial question that you can research with Google in a matter of minutes. Please make some effort on your own, come back here and demonstrate that you have made the effort, and tell us your understanding of the situation. Then, I will be happy to help clarify your understanding, if necessary.
 
  • #5
well i found out that dc flows in 1 direction and is useed by cpus, micro electronics,recharging storage batteries.

and that ac goes 1 way then goes the other way 60 times a second and that is can be generated by wind, water, nuclear, oil, and that the generators use magnets and that ac is used in power outlets.

but i just can't find how DC is GENERATED i googled it several times with different key words but it comes out with stuff too complicated for me to write and if i do my teacher will suspect something b/c I am in the 8th grade so can any1 help me with that like give me a website that explains that part??
 
  • #6
HINT! You can smooth and rectify AC to produce DC. Pay attention to "rectification" because that word will be your friend. Good luck!
 
  • #7
thanks for the hint but i don't see how that explaines how dc is produced
 
  • #9
oh come on, I'm not that smart I am only 14! our probe classes haven't even tapped into rectification!
 
  • #10
well does anyone know how DC can be generated from AC?
 
  • #11
halfANDhalf, if you ever expect to understand electronics, you have to grasp the concept of rectification. I can't spoon-feed it to you unless I want to spend hours and hours explaining it. Please Google it. Hint: Turbine-generator sets are designed (with rectifier circuits) to charge the batteries that are used to "flash" the generator on start-up to create a field that can be used to get the generator producing power. Every large generating station uses both AC and DC power to do their magic. I understand that you are only 14, but when I was a child, I lived in a tiny town with a very large hydro-dam and the operators knew me and allowed me to visit the power-plant from time to time. The battery-room (all DC) of a large hydro-dam can be huge and daunting!

I understood field flashing 'way before I was 14 - at least on some level.
 
  • #12
oh ok thanks but when u said if i want to understand electricity i need to know ratification or wahtever i just don't know that far into electricity so when i get there i will better understand what you said
 
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  • #13
never mind i found it out it means : conversion of alternating current to direct current right? thank you
 
  • #14
Listen! You can take alternating current and run it through a tube rectifier or through a capacitor-based rectifier and make DC out of it. It's also possible to produce DC that has AC-like ripples.

Study! Please take the time to research electricity and learn - then come back with questions. If you are serious about learning, I will help you, and others will, too. If you keep posing general questions about very basic concepts, people will ignore your posts and you will not benefit.
 
  • #15
halfANDhalf said:
well does anyone know how DC can be generated from AC?
As Turbo indicated - rectification. Please show some effort by oneself.

For small voltages and currents, simple diodes are used in a diode bridge, but for large power systems, silicon controlled rectifiers (SCRs) are necessary. Also, its better to use multiple phases, with each phases out of phase, such that as the voltage of one phase is decreasing, the voltages of the other phases are increasing.

This site might be helpful for understanding electronics and electrical theory.
http://www.allaboutcircuits.com/vol_2/index.html
http://www.allaboutcircuits.com/vol_3/index.html


An alternative method, and less efficient would be to use an AC motor to drive a homopolar generator (HPG).
 
  • #16
the best thing to do is to buy a book.
i've found the internet pretty good for buying stuff
and communications and entertainment.

pretty darn useless for learnin about anything
[with sites like this an exception of course! :p]

in college when i wanted to know something i'd sometimes spend 1~2 hrs googleing etc etcetc and not get very far.

then i'd go to the library, spend 10 mins finding the right shelf!
20~30 mins finding the right book.
and then another half hour or more reading.
ppl get paid to write books, the internet is free. you usually get what you pay for.
for the basics and broad, [introductions] buy a book and read it.
for specifics or opinions or ideas use forums!

almost every subject in the world has many many books written on it.
and most of theese are titled

"bla bla bla", An Intoduction to "bla"
 
  • #17
turbo-1 said:
Listen! You can take alternating current and run it through a tube rectifier or through a capacitor-based rectifier and make DC out of it. It's also possible to produce DC that has AC-like ripples.

Study! Please take the time to research electricity and learn - then come back with questions. If you are serious about learning, I will help you, and others will, too. If you keep posing general questions about very basic concepts, people will ignore your posts and you will not benefit.
Oops! I didn't review before posting. Common SS rectification circuits are made up of diodes, not capacitors. Capacitors are used to take out the ripples and smooth the DC after it is produced. This was common in guitar amplifiers from the '60's on. Until the '60's most amps used rectifier tubes but as the power-handling and reliability of diodes improved, diodes often got the nod. Since diodes *can* fail under reverse bias, they were often used in series. IIR, the Fender Twin Reverb design employed series chains of 3 diodes on each leg of the rectifier circuit.
 
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  • #18
i already found that stuff out now besides i already looked it up bnut thanks any ways you guys really help out on my exam
 
  • #19
halfANDhalf said:
i already found that stuff out now besides i already looked it up bnut thanks any ways you guys really help out on my exam
We will ALWAYS help if you come here having covered the basics on your own and want help with the details. Everybody here who helps with homework and studies is volunteering their time for free and we all have jobs, school, research, families, etc that take up much of our time, so we appreciate it when students with questions will do as much independent work as possible and then pose questions when they hit a snag. If it were not done this way, we couldn't help anywhere near as many people.
 

1. What is the difference between alternating current (AC) and direct current (DC)?

Alternating current (AC) is a type of electrical current that changes direction periodically, while direct current (DC) flows in only one direction. AC is commonly used in household and industrial electrical systems, while DC is used in smaller electronic devices, such as batteries.

2. How does alternating current differ from direct current in terms of voltage?

AC voltage constantly changes from positive to negative, while DC voltage remains at a constant level. AC voltage is able to be easily transformed to different levels using transformers, while DC voltage cannot be transformed in the same way.

3. Which type of current is more efficient?

In terms of power transmission, AC is more efficient due to the ability to use transformers to increase or decrease voltage. However, in terms of energy consumption and cost, DC is more efficient as it does not require as many conversions and can be used directly by electronic devices.

4. What are the advantages of alternating current over direct current?

One advantage of AC is its ability to be easily transformed to different voltage levels, making it more suitable for long-distance power transmission. It also allows for the use of smaller and more efficient wires. Additionally, AC generators are simpler and more reliable than DC generators.

5. Are there any safety concerns when using alternating current versus direct current?

Both AC and DC can be dangerous if not handled properly, but AC is considered to be more dangerous due to its ability to deliver a higher voltage and the fact that it can cause muscle contractions. However, proper safety precautions should be taken when working with either type of current.

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