Alternating current, direct current & what is frequency? | Physics | Khan Academy
ฝัง
- เผยแพร่เมื่อ 16 ต.ค. 2024
- 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.
More free lessons & practice www.khanacadem...
Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!
Donate here: www.khanacadem...
Created by Mahesh Shenoy
He is the ONLY physics teacher who asks, 'does that makes sense?'🥰🥰☺☺
He isn't
Asin eh 😂❤
Khan academy is really a blessing from God for students 💜🙌
yeah it is:)
Hello Ji
The best thing about him teaching physics is that no matter how new you are to the topic , you understand it because he chooses logic over so called "laws"
Current comes in two flavours ☺️☺️☺️☺️☺️
Edit : unexpected number of likes
😆😆😆
We can,t taste it but still funny 😆😄🤣😂😁😀
You tasted it didn't you? Blink if you're still alive my friend😂😂
In particle physics there is actually 'flavours for particles'
Itne likes expect nhi kiye the yaha se
You are a teacher dropped from heaven 🌼
This is the best video i have ever found on this topic 😍😍😍
Thanks a lot 💌💌
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
Dude…ok so day after is my boards and this guy just shows up with the best lecture???
I wish I watched ur videos before
Same dude..
I was looking for a video for my students and came across this one - excellent. Its well explained and thorough.
Excellent explanation. Understood really much of everything about it. Thank you.
Excellent video. Clear explanation 🙂
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
Mahesh Shehnoy---- Superb teacher❤️
For me -
This is the most bestest best video for clearing my doubts 😅
I got the answer which I was eagerly searching for!!!
Thanks a lot sir....it left no doubts...!🙂
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 .
I wish I had access to this videos 35 years ago…how much money and time my parents would have saved!!…
I too wish I had..
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).
Good question..
Thanks a lot.
No one was answering me about why AC?
My doubta clear now...😍
Thank you sir for this amazing explanation . 👏 Lots of respect
Most underated 5* rating channel.....Awesome yar love you khan academy
Thank you so much sir!! I was curious about this question : Why AC and not DC..??... But now I got it cleared sir... Thank you 👍🙏
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 ?
Thank you sir. I finally understood this 🙂💖
u have a very friendly voice thankyou for the video
i have no words to say about your explanation . it is very very easy to understand i love you sir
OMG concept of teaching 😯
Well I used to think it's a camera problem
Watched few vdos about AC and DC, but this vdo at basic level, layman's explanation.You've got a subscriber!!
Fascinating... I knew nothing about electricity and I thought transformer do the opposite of what you just shared. Now I know better
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...
@@omm12459 you're right
@@LearnInnovateAI i have written 2 things .... which one is right?🤔
@@omm12459 both, it's the energy that's being transferred by making electrons swing back and forth
@@LearnInnovateAI oh... Thank you
I also try this with tubelight it's fun👌🏻
Sir actually i have seen many 1 hour long lectures on the topic but everyone repeating same....this 12 min. Video was like a doubt solving session
Make every chapter in hindi+english also sir because it will be good for us students from non english school to understand the concepts khan academy is fabulous no match for khan academy😍
Perfect teacher love 😘
well explained sir... absolutely wonderful video
Excellent explanation 👌. Thankyou so much sir!
Just watched the video...liked it and subscribed❤️
Wow, best AC and VC video for beginners.
My favourite channel
and the best teacher ever i have seen
Amazing!!! Awesome teacher 👏
No ads.🤩
Very good explanation
Finally doubt clear🥵
Thank you sir❤️
Thanks khan academy, you are da best!
can the magnitude of dc current change?
Current come in 2 flavours 😁0:38
Sir, I have a doubt.... if one electron is moving through the bulb for many times back and forth, then it should have lost its energy . But it hasn't. The bulb still glows brightly, 🤔
Thanks 😊
Great video thnx 🎉❤
Woh!! This lecture made my day!!!!
Best video about intro in AC
Thank God i found this channel 💜🙌
you have saved a student Alottt
Gamsahabnida .. ,,, 🙏
Tysm for the explanation.
Why the electrons flowing in A.C current moves back and forth, is it just to imagine or is it actually how it works? Well electrons bounce off of 1 atom to another, so does that mean it bounces and then bounces back to the same atom again? I can't understand why the electron are moving back and fourth in the A.C current.
Thanks for helping student
My heartful thanks to khan academy
Thank you so much sir
What will happen if the current is too high??
Excellent!
This guy is amazing
Ur in other level of explanation 🙏🙏🙏🙏🙏🙏
Ap Bada bada thanks bhaiya ,
Good explanation with brief
Very interesting sir
Whoa! Thank you so much
It seems to have a relation with persistence of vision
What will be frequency of an A. C if its direction changes after every 0.01 second?
As direction changes for 0.01 sec, and also one cycle is of 2 directions, that implies 1 cycles takes a time of 0.02 secs... Frequency = 1/Time Period, here time period is 0.02 secs.... therefore, frequency = 1/(0.02) = 50 Hz... Hope this helps
Excellent experience
ur such grate teacherthank you very much .....
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 ?
It is really a very amazing channel with free of cost 👏👏 and a lot of videos
Excellent and Brilliant!!!
Why can't we send low dc current and use the transformer to step up the current
Thanks sir
Excellent
Sir I have dought on AC current ?
Current means flow of elections or charger particles ,that means current is moving ,ln AC current the charge particles does not move it just oscillat in the same place then how the current flow
amazing.......really a big blessing from god
Sir do the electrons complete one complete cycle throughout the circuit before changing their direction?
Totally depends on the frequency of alternation, the strength of the current, & the length of the wires
At high currents (high speed), low frequency (more time to alternate), and smaller circuits, electrons might complete multiple loops before changing direction.
Whereas in low currents, high frequency, and larger circuits, they might be just oscillating back and forth!
@@KhanAcademyIndiaEnglish Thank you so much Sir for answering and making my concept clear🌺
@@alilbitofbakht2626 congratulations bhai aapko reply mila Khan academy se
bro you are great once in a life i will meet you❤
When current flows through a bulb in our house, no short circuit. But if in the place of bulb a conductor is used, short circuit follows causing devastation. I do not think only consumption of electricity of the bulb can explain the thing.
Best teacher
beautiful lesson:)
really great video , just a seizure warning would have been nice on the flickering tubelight
Your are really awesome salute you
Nice
What is the name of the board program he is using?
very clear
In this video you said that 100 times per second current change but in phasor video you said 50 time per sec. Which one is right one.
In ac, if it moves back and forth, then how electron will reach destination
GOOD QUESTION
Same question bro
Wasim i found answer later bro
That electron will not move from source to destination.
Electricity is the movement of electrons
i.e electrons dont need to move from one place to another.
When the electrons just move front and back, the electricity is produced.
@@srinivasan3615 answer this question
Why fan not rotating or changing its direction in one cycle of wave ?
Why it is rotating in single direction? Bulb glows and offs
In that case fan rotation should alter
Aravindh Gunti fan converts electrical energy into kinetic energy
(Disclaimer: i m not a eee student 😂
I know just the basics)
Thank you so much 💖💖💖💖
Ty Khan academy ❣️
Toooooooo good 👌👌 explanation sir . thank you so much 🙏🙏
Brilliant explanation, best video on this topic
Sir, please answer ,"why fuse is connected to live wire only"?
Rohit Nagwal
Fuse is connected with the phase wire(live wire) as the electric current flows from the live wire to neutral wire, hence in a case when current increase the live wire will get heated first as current flows through it first and then goes to the neutral wire.
So in cases of voltage fluctuations the flow electric current needs to be stopped hence the fuse is connected with the live wire.
@@anmolrajput9133 live wire doesn't carry all the current.
As current is a flow and hence it flows from live wire to neutral wire
Because if fuse is connected to neutral then in case of short circuit the fuse wire will break but still current with flow till electric appliance as it is still connected to live wire so, we may get electric shok if it is not connected to earthing.
It's science of course 💨
Very good explained 👍👍
West or east khan academy is the best
..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..?