Alternating Current

[fizzizat]

hogwash!

[530BigBen]

BullShit, There are many flaws and flat out lies to this video. This is possible if every home was generating their own electricity. Because you need a substation every 2 miles to maintain a strong DC current. Laptops/anything with a battery run off DC, the converter is in the charger not in the computer, the heat from a lap top is from the integrated circuitry. Answer to the problem, Don't plug your solar panels into the grid, use it for charging batteries.

[ZombiedustXXX]

Canadian David Stringer is quite a character! His style was rather flat, but always earnest.

I saw his stuff in the US many years ago, and he was always an inspiration, in that he got one's mind to ask more questions.

AC power being sent to homes has not always been 60Hz. There were varying standards across the US. I saw a cool and old desk clock in my father's garage. He said it would not work, because it was made for 50Hz AC. Sure enough, it ran too fast on 60Hz power.

[hitachi088]

@ZombiedustXXX Japan run on 110V-100V AC 50Hz.

[DarkTahmi21]

Wow.. man... I'm jealous.. you have so many equipments... :D

[Serostern]

He has a REALLY nice mains sinus wave! I have NEVER EVER seen any that smooth!

[bigbossdeleon]

6:09 what happened there? Why did the graph change?

[Marty1fatbstard]

The 60 comes from the fact that the UK uses 50 and not being happy at being the same the americans went 10 better..... However when the UK realised this we doubled our voltage.

[metro2089]

Did you plug your oscilloscope directly into wall, I was told this was safe did it and blew a breaker in my house?, says its rated for 10kv, the scope was also connected in parallel with a motor to act as a load, i did it both ways direct and in parallel?

[tomo25252]

1:11

The work that's done by the current IS NOT measured in watts, but in joules. (watt hours) It's the energy that you consume, because the work is the energy in transfer. BTW, that determines how much you pay for your electricity bills.

[prateeksharmabittu]

wow u r awesome man !! i have a doubt . what does negative half cycle mean . if a current is movin in a particular direction on the positive half cycle does it reverse its direction or it only reverses magnitude on the negative half cycle. if magnitude reverses how can a -ve magnitude exist ??

[acmeschool]

@prateeksharmabittu

It's direction. although some days I feel negative magnitude....

[AnnaKin]

thank you! this helps me understand it so much better!

and I probably should give a shout out of thanks to Tesla too :D

[JettaJ1]

the four thumbs down hate science. dont worry science hates you too:)

[NIXYSKILLA]

TESLA!

[gambart2002]

What an awesome video.

[MrDohmah]

hey i have a electricity-related exam for school in a few days. can somebody please explain to me why in an AC generator the output voltage is negative-positive-negative-pos­itive

[lmeister3]

Bill Nye vs. this guy in a street fight. Who would win?

[lmeister3]

This guy could be the living shit out of Bill Nye.

[BaltoMovie]

4 people have an iq of 76

[newrapsux]

nice. about time someone puts up a video that makes since and isnt filmed by grandpa flanders.

[justmecoop]

The Human Eye will detect lights flickering if the cycle is less then 60 hertz 60 or above the eye cannot see the flickering 

[mikero1369]

60 seconds in a minute.

[67tr876]

@mikero1369 no 60 times in a second.

[PAM2167]

Great tutiorial but I'm still left with questions?

[PAM2167]

Volts times amps equal watts. Ok well what does 1 volt =

[BaltoMovie]

@PAM2167 how many amps?

[PAM2167]

Ok so correct me if I'm wrong. VOLTS is the force electrons are being pushed thru the wire? AMPS is the number of electrons flowing through the wire at a given time? I never knew transformers stepped up the volts. I always thought they stepped down the volts to the proper amount needed to power the device without blowing it up from too much voltage?

[davidstringer1950]

I have never been comfortable with the speed/force/amount analogies of volts and amps... not because I'm an expert, just because I don't have the correct gut-feeling for it. The volts are the potential for work. If you put a bucket of rocks on a table, it has more potential for work that if it's on the floor. The amps are the electrical current. Bigger=more. The volts TIMES the amperage equals the work.

Transformers go either way, like gears.

Maybe wikipedia can clarify.

David

[metro2089]

@PAM2167 one side steps up one side steps down, can be used either way

[SickKnowledge82]

Thanks man, very useful and helpful information.

[rollingroses]

how does the AC current reach destination if it keeps coming back and forth ?

[acmeschool]

well, there are several ways to think of it... The first off the top of my mind isn't great, but Imagine that you are sanding a chair rung with a long strip of sandpaper held in two hands. as you move your hands back and forth, the rung is still getting sanded. It's the movement of the electrons that does the work, not the direction that they are flowing. does that work for you?

David

[rollingroses]

what I mean is : let's say the wire is spread on a very long distance, like the ones coming from the power plants to eh households. How do the elctrons go from the starting point of the wire to the end if they keep coming back and forth ? Do they get to the end instantly and then go back to the start ?

[Azkynova]

@rollingroses

They don't travel that far. The electrons are already in the wire, and the generator pushes more electrons into the wire and makes the chain of electrons move. Let me explain: Imagine that the power line is a tube and the electrons are marbles. You push a marble into one end of the tube, and another one comes out at the other end. Understand?

[NJRocks281]

there is no destination

[MohammedIbtehaj]

well AC doesn`t change direction until it first reaches the positive terminal.

[ROBATOID]

Who is this man? This looks like it was shot in the 1980's? I thought transformers step down the current?

[acmeschool]

Hi Robatoid,

Step down, yes. Turn it around, and the same transformer steps up! when volts go up, amps go down, so the voltsXamps stays constant (except for efficiency losses in the transformer)

[DuffBeerDragon]

@acmeschool - what's the ratio of windings for the transformers primary and secondary windings to one another? ie - how much can you step up the current or volts before there isn't enough of them coming through?

Also what would you use to split a power source and control how much current and amps / power goes to each path? How do you join them back up again?

Hope you don't mind me asking...it's hard getting this info even from off-the-grid books.

[67tr876]

@ROBATOID step up or step down

[vrjim]

@ROBATOID show is the Acme School of Stuff. Host is David Stringer

[richard8587]

nice

[Grundalizer]

WHY THE .707???????

[Serpico261]

lets say u have a sine wave with 1 V...then u have to calculate the RMS value.

1 Vpp = peak to peak

RMS Value gives u the correct voltage value when u want to calculate the Watts out of it.. lets say we have 1 amps and 1 Vpp...then u load resistance does not waste 1 watts (V x I = P ??), why?

because in the sense of work the circuit only wastes 0.707 Watts....

1 Vpp x 0.707= 0.707 Voltes RMS

0.707 comes from the phase of an sie wave (sin 45°)

[Grundalizer]

the sin of 45 is not .707. 0.707 is half the square root of 2 , which i remember using for some calculutions to get RMS or VMAX

[Serpico261]

yes i know...but its the same...sine function is nothing but trigonomy and its equivalent to sin 45° or half the square root of 2

[xplorsonu]

@Serpico261 Brother what you told is only true for ac sine wave, isn't it ?

[Serpico261]

@xplorsonu actually all AC wafeworms share the same property. For example an AC sine wave like the one in your home has a perfect 0,707 coefficient to its Peak voltage. i made a mistake above..i wrote peak to peak....its only peak voltage.

if you have a square wave with a duty cycle of 50%, meaning half the time the signal is on 1 v peak and half the signal is off 0v, than you have a coefficient of 0,5. So when you calculate power, than you write 0,5 v * I current, and NOT 1 volt * I current

[Serpico261]

@xplorsonu actually all AC wafeworms share the same property. For example an AC sine wave like the one in your home has a perfect 0,707 coefficient to its Peak voltage. i made a mistake above..i wrote peak to peak....its only peak voltage.

if you have a square wave with a duty cycle of 50%, meaning half the time the signal is on 1 v peak and half the signal is off 0v, than you have a coefficient of 0,5. So when you calculate power, than you write 0,5 v x I current, and NOT 1 volt x I current

[xplorsonu]

@Serpico261 so the 0.707 coefficient is not applicable for DC sine wave and the Square waves represent Direct current only, right ? Thank you

[xplorsonu]

@Serpico261 Thank you very much Serpico for taking the trouble to clarify my doubts. Actually I read a book yesterday that said "AC voltage is usually specified at a value equal to the dc voltage capable of doing the same work. For a sine wave this value is 0.707 times the peak voltage known as the rms voltage." and today when I came to know that not only AC sine wave but also DC sine wave's RMS voltage is considered for calculation of Power...I got a little confused.

[xplorsonu]

@Serpico261 And today when I saw people telling how RMS power mattered more than just Wattage for speakers, I was even more confused about the RMS's definition. But hey, now I see AC square waveforms too on the same book. However, I won't stop thinking......thank you so much for your time friend. I feel nice I learnt something new today that made my day. Thank you again

[Serpico261]

@xplorsonu your welcome. Its a fascinating subject, i love talking about this stuff. If you are interessted in electronics there is one website "allaboutcircuits(dot)com" they offer videos and..this is really the best, you can download textbooks that cover a variety of subjects in electronics. Its one of the best material that i have seen so far. You have to check this website out.

[xplorsonu]

@Serpico261 yes I have seen that website a few times before......I didn't know there are videos also. Thank u so much for letting me know that. I can also see the forum there.....very intriguing. Thank u for letting me know better about this website again. I am going to hook around it from now onwards regularly to make myself clear at topics related to electricity or electronics. And do u know yahooanswers(dot)com ? There are several great answerers there also.

[Serpico261]

@xplorsonu hang on dude, i made a mistake...gosh i did not noticed that. im sorry, if you have this clipped sine wave 2 Vpeak than you have a 1 Vrms (50%) so you calculate 1 Vrms x Current.

so you always calculate 0.5 x V peak of the DC sine wave = Vrms. And this RMS value is used for power calculation.

[xplorsonu]

@Serpico261 But by doing so we would be treating a clipped sine wave like a perfect square wave.......is that fair ? or may be I am mistaking somewhere.

[Serpico261]

@xplorsonu sometimes i typed in some questions related to electrical engneering and i always found a forum that addresses these questions, i think i remember that yahoo was included.

About the clipped waveforms,take a DC triangular, sine or square wave and fill the space for one period under the voltage line and you will see that the filled space equalls the non filled space.These clipped waveforms are symmetrical and therefore you calculate 0,5 Vpeak, so yes ur right.But for AC its different

[Serpico261]

@xplorsonu in AC its confusing when you deal with that for the first time.

AC sine ( 0.707 ) DC sine ( 0.5 )

AC triangular ( 0,5 ) DC triangular ( 0,5 )

AC square ( 1 ) DC square ( 0,5 )

The reason why a AC square wave has a coefficient of 1 is because its negative half cycles carry a negative voltage. You have to imagine a rectified waveform, where the negative parts are made positive, so on AC square you get a straight line and therefore your Vpeak = Vrms 

[xplorsonu]

@Serpico261 So here it is where we met last time Serpico.......it's 2 weeks ago as I can see......I was glad to see you on the other video of a Computer Organization lecture.

[Serpico261]

or just think of a square wave. amplitude is 1 Volt..but when u multiply it with 1 amps u waste only 0.5 Watts

this is because a square wave returns to zero volts, as much as returns back to 1 volts for the same time

so: 50 % of the signal is 1 Volt and the other 50 % is 0V

so when u only have (in terms of V x I ) the half of the voltage u have simply 0,5 Volts

so calculate the RMS voltage of 0,5 Volts times 1 amps = 0,5 Watts !!

[Serpico261]

in a sine wave we have the same situation but u dont multiply the Vpp with 0,5 like in the square wave ( 0,5 duty cycle)...we use 0.707 because when a sine wave period is 100% and when u fill the sine wave space with a marker, then u have only filled 70,7 %.

[krqtos]

.707 of the maximum current, is the RMS current. This, the RMS current, is the assumed current for AC circuits.

Were it DC, you would just use the regular max current.

Also, note that .707 is just the decimal value for the square root of two.

[rhizopogon]

@krqtos

actually, the square root of two is around 1.414.

.707 = ( sqrt(2) ) / 2

[krqtos]

Oh, if you want me to get more boring and tell you why the square root of 2, I can, just let me know.

[brevgo]

Very shocking

[zignosband]

Hi Sir, how can I download this video. It's really interesting.

[z0z0z0ify1]

i believe th answer to th 60 hrtz question is explained in the utube vi, "Intro into electronics Part 2 Alrternating Current v1.

[flashydee123]

Interesting and informative...u gotta love electricity :)

[lemieuski]

The frequency of AC is needed to reach the proper electrical resonance, imagine someone on a swing, you push them just as they are done with the last arc, same goes for AC. Capacitors and inductors charge and discharge causing changes in the magnetic field which translates to the frequency. In the U.S. our AC's frequency is 60Hz

[patrick5158]

WTF u a scientist??? I luv UUUU woooahhhoo!!! Be my teacher! haha jkjk

[MarcusDM3599]

I agree, Tesla doesn't get enough credit and this is one of the most informative videos I have seen about electricity

[jekyll3hyde]

yeh 60 Hz is american. its 50 in australia

[latviski]

and Europe

[esQo0020]

60 cicles are maybe random ..in europe...atleast in serbi... its 50 Hz

[GUILDGOB]

Maybe they chose 60 because thats what the average human eye refresh rate is at, or at least thats what I've heard. Would keep the lights from flickering visibly to the human eye.

[briphillips29]

Telsa knew edison was full of sh**.

Hope this helps in some understanding of AC 60hz.

Oh and to support my claim just take a look at the power over seas.Its 50hz. Where edison had all the rights to the power at the time.

[briphillips29]

There is no revalance inbetween 60hz or 50hz.Tesla and edison was fighting over AC and DC.Well when tesla won edison was still tring to get back at tesla and he wanted to keep his name in the loop so edison was saying 50hz because of his light bulbs(plus he was tring to say if someone did touch the wires they would be able to get away from the wire.While at the same time tesla was saying 60hz would light the buld at a more steady rate.

[jayguy173]

the genarator turnes 360 degrees and 60 is 60 degrees and 120 is 120degrees

[WrongTimeline]

7:55 of airtime most expertly filled.

THX David!

[boxa888]

great video, but i wish you gave tesla credit! everyone look up nikola tesla, hes responsible for ac power, xray , florecent bulbs, radio, wireless power transfer, even basic logic circuits which lead to your computers and cell phones. the list goes on and on!

[CJackSparrow79]

wnderful

[jnwpse]

the 60 is the speed measured in hz. hertz is the frequency ..or the reciprocal of the period.T=1/f......(I think im right at least)

[HumbleLife]

tesla, tesla, tesla, pssst,

tesla

[acmeschool]

Hi Hmblelife,

You have a point. I don't know why the electric company's research material has so little to say about him. Everyone go read about Tesla on Wikipedia now.

David

[hystat]

This whole Acme series was produced in a 2 day weekend. David is "winging it"...

Modern day, so called educational channels should be ashamed

[acmeschool]

Hi Hystat,

Just a small correction... Acme was concieved and mapped out in a two day weekend. It was an emergency screw-up that left me with a budget, and air-time for 13 shows, but my high-tech content was nixed. I had two days to come up with a show that was low-tech. Acme is named after the toilet in my basement, seen at the beginning of the toilet show...

[Youngwolf27]

yea but we give credit to him now but back then since Tesla sold his invention it was then called the westington invention

[oozt]

did he said the westinghouse invention?

the transformer was invented by Nikola Tesla not westinghouse, westinghouse did only fund his experiments (Teslas)

[Youngwolf27]

No Tesla sold his AC patent to Westington.

[amirfarid91]

tesla should still be credited

[sypha0x]

Doesn't matter Nikola Tesla was the Inventor.

[Electrotime]

are you good with cuircut boards?

[jazzGT]

cool