Electrical Engineering: Ch 10 Alternating Voltages & Phasors (7 of 82) Adding Sinusoidal Functions

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In this video I will explain how to find the phase angle difference between two phasors and how to add to phasors together on a phasor diagram.
Next video in this series can be seen at:
• Electrical Engineering...

[@smcm9977]

Thank you so much for this video series. I am currently in a ciruits class and the instructor does not do a satisfactory job of lecturing. Your videos are extremely clear, concise, and well paced. Again, thank you for everything you've done.

[@righteousness185]

i've seen your other videos, excellent teaching. I like how alot of your videos are about 5 minutes, yet very comprehensive at the same time.

[@ahsanhabib8877]

Thank you sir. You can make things so easy to your students. Love from Bangladesh.

[@MichelvanBiezen]

Welcome to the channel!

[@aaron447]

Hi, your math was indeed correct, but you made a small oversight which is causing some students to be confused. You should use the identity -cos(wt) = cos(wt+180) = cos (wt-180), which is the equivalent to what you wrote, but matches your work better for v1(t), since we are adding/subtracting 180 when the amplitude is positive, not negative. It is similar to why we are subtracting 90 for v2(t) when the amplitude is positive.

[@rrekeitebetse6936]

I think there is something wrong, if we want to change from sin to cos with keeping positive sign, just add 90, but if we subtract 90 we will get negative cos, isn't it? I know sinx=(cosx-90) and cosx=(sinx+90) and here we are intrested in finding cos in which its supposed to be + 90. revisit it and look at it precisely , they are not the same and they will not give the same answer. I appreciate ur work sir

[@MichelvanBiezen]

What do you think is wrong in the video?

[@Nataleyb3]

@@MichelvanBiezenthe part where you subtracted 90 was wrong……..you were supposed to add 90 since you’re going from sin to cos= +90

[@stefanleo9048]

Thanks for teaching the theories.... I finally solved my task!

[@JoshuaWGbuah]

Thank so much, I have been struggling to understand this topic. Sure you are a legend.

[@GERBINO01]

michael you said it doesnt matter if you add or subtract 180 to change negative to positive but if you say 60 +180 it gives you 240 and if you subtract 180 from 60 you get -120 it produces different answers

[@MichelvanBiezen]

-120 is the same as +240

[@GERBINO01]

Michel van Biezen thank you so much

[@rjaph842]

@@MichelvanBiezen thank you so much.i hd the same concern too

[@EigenA]

I’ve never seen axis set up like this. I understand a -90 sin shift results in a cos and therefore there is nothing incorrect about the setup but is the purpose of this just have a graphical representation of phasors?

[@azizmizrobov4058]

Changing V2 from sine to cosine, can we say 3sin(wt-20+90)=3cos(wt+70), as we know sin(wt+90)=cos(wt)

[@andyjunior]

I thought so too. Must’ve been an error

[@aaron447]

No, because we are supposed to subtract 90 to the cos function. You are adding 90 to the sin function, which is not what you are supposed to do. Change the +sin to +cos, then follow the rule cos(wt + Φ -90). For v1(t) use -cos(wt) = cos(wt + Φ + 180) = cos (wt + Φ -180). Change the -cos to +cos, then follow rule cos (wt + Φ -180)

[@nareshchandraverma5721]

Q. Two identical spherical balls of density D are suspended on vertical threads at a distance r from each other in vaccum. The balls are given equal charges and immersed in a liquid of density d and dielectric constant K. If threads are not deflected from the vertical in vaccum as well as in dielectric liquid. Then

[@joshuaflores5741]

You are the best! Do you have a website similar to the KZbin tutor, Math and Science?

[@MichelvanBiezen]

Our videos are organized so that they will take you systematically through the material as if you are taking a course.

[@joshuaflores5741]

@@MichelvanBiezen I am taking electrical engineering and you above all else are a big help! My Engineering instructors pale in comparison with how you teach! Thanks! From the Philippines!

[@MichelvanBiezen]

Glad to hear it, and welcome to the channel!

[@mohammadgholami839]

Hello, thank you for your excellent teaching. I only had one question. In the figure on the top right, when we lower the cosine by 90 degrees, we reach the negative of the sine. Why did you write positively?

[@MichelvanBiezen]

When we are dealing with phasors and phase angles, we want to know the relative phase difference between the cos and the sin. The sin reaches a maximum value 90 degrees "behind the cos in the phase measurement"

[@arvamin5896]

The best professor ever ❤❤❤❤❤

[@MichelvanBiezen]

Thank you. We appreciate your comment. 🙂

[@fachriyasir661]

sorry I'm new to this, but why should we change them to positive cosine form? can we change them to positive sin form?

[@sam-kx3ty]

To invert the negative amplitude of v1 why can’t we add a positive 180 degrees? Thanks as you reply .

[@MichelvanBiezen]

Yes, that works as well

[@ahmedal-ebrashy3691]

Sir is there a reason that the positive sine is draw downwards axis. I find it counterintuiive that addidng -90 give positive sign but these are things arbitart we have invented it. Special thanks for your effort and MRS BIEZEN THANK YOU SO MUCH FOR THE EDITING, AND PRODUCTION. lotos of love to both.

[@MichelvanBiezen]

Thank you for your comment. Remember that these "vectors" are actually phasors, which means that they continually move around the circle according to (wt). Wherever we draw them it is simply a momentary snapshot. A moment later they will be in a different position. The phase angles are relative to the current phase through the resistor.

[@Nataleyb3]

@@MichelvanBiezendo you mean we can either add or subtract 90?

[@brindhagopalan7105]

Really good explanation, please do keep making more videos so we can understand

[@munnamonk7608]

Wish I would be taught in my class likewise 😅. Thanks Sir ❤️🙏

[@SS-pn7ss]

Very very well explained, exactly what I was looking for: thank you.

[@MichelvanBiezen]

Glad it was helpful! 🙂

[@thabisombingo9649]

shouldn't you be adding 90 degrees when moving from +sine to +cosine?

[@MichelvanBiezen]

In the context of phasor diagrams, the sine finction is 90 degrees behind the cosine function as the phasor diagram rotates in a counter clockwise direction.

[@my-rv8nc]

Thank you professor for the great explanation, i have only one question why you didn't add +90 to sin to become cos but you subtract -90 can you explain that?

[@MichelvanBiezen]

The best way to look at it is this: Cos (theta - 90) = sin (theta) Now let theta = 90 degrees and you'll see they are equal.

[@my-rv8nc]

@@MichelvanBiezen thank you professor ❤

[@lakhvinderlucky07]

What if V = V1+V2+V3

[@fachriyasir661]

sorry I'm new to this, but why should we change them in positive cosine form?

[@DarkRedZane]

Actually, you'll be fine with just sine, but we change it to cosine because it's easier.

[@mayankkaushik1091]

@@DarkRedZane why you did not take sin( theta + 90) because you are converting +cosine not -ve cosine

[@charlesenricosalinas5368]

How to identify if you will add 180 or subtract 180 degrees if you change -sine to + or -cosine to +cosine? pls reply thank you!.

[@Himothy22B]

Usually if the angle before changing is negative you would have to add 180 but if its positive you would subtract 180. This is so that you always remained in the range of -180 to 180 for your final conversion

[@josiahmpasa9478]

Thank you for your video. I get so confused about how to use the formulas provided in video 3/82. How do you know whether to subtract or add 180 to the phase angle to change it to the positive sign of v_1? Does it matter? I also got confused about converting v_2 from sin to cosine, aren’t we supposed to add 90 degrees to sin to get it to cosine?

[@MichelvanBiezen]

It doesn't matter (adding or subtracting 180 degrees), the result will be the same. And the cos (0) = sin (90)

[@josiahmpasa9478]

Thank you so much!

[@iya7428]

why did you do 20 - 90 not 20+90??? shouldn't you add to get the same sign when changing from sine to cosine??

[@MichelvanBiezen]

Try out the numbers on a calculator and see what happens.

[@kmbstar]

Thank you for this reply, it may seem elementary to someone as advanced as you but the simple suggestion of plugging it into the calculator and me actually doing that now means that I'm feeling more sure about manipulating these equations especially for finals. So thank you for your videos, thank you for your suggestions and interactions with us. It really means a lot. We are lucky to have you and I look forward to seeing more videos and learning more, and hopefully Acing my circuits final and getting that A I've been working on all semester as well as a deeper understanding of how all of this works since I'm working on electrical engineering and computer science majors. Thanks again!!!! @@MichelvanBiezen

[@aljohnson3717]

Should the positive Sin be in the First quadrant????

[@vijayraj521]

In -cos we can add +180 also to get cos

[@tsehayenegash8394]

I have 15 years ardiosonde temperature data. I have the amplitude of this temperature data. how can I get the phase change from this data? thank you.

[@MichelvanBiezen]

Not sure what you are asking for. I would need some more information to potentially answer that question.

[@tsehayenegash8394]

@@MichelvanBiezen I have 15 years Radiosonde Temperature data. The radiosonde measure temperature from the ground to an altitude of 36 km after 36 km the radiosonde is burst. I did the amplitude of this temperature data (Amplitude= Temperature - mean Temperaure and take the peak one). This peak temperature tells the dynamics of the atmosphere(QBO, AO, SAO,TAO). I have got a problem to calculate the phase shift by using this real data?

[@MichelvanBiezen]

Are you referring to the phase shift of the carrier signal (which is caused by the doppler shift of the moving device or by the time difference between the sender and the receiver, or are you referring to the phase shift of the temperature data? What data is the phase shift referring to and what is the cause and concern of the phase shift. Note that you need to know the frequency of the carrier signal and the delay in getting to the receiver in order to calculate the phase shift.

[@mayurambhore2051]

Thank you very much sir, I was facing so much problem while solving this type of sum

[@YomTech44]

10Q so much sir....u done well

[@AbhishekKumar-hb5uj]

thank sir it is helpful for me.

[@kiprotichrono2105]

what if it was three variable let take as A,B,C

[@aimanzulhakim5476]

Thank You very much for helping me

[@MichelvanBiezen]

Happy to help

[@sarakhaled8986]

I think there is something wrong, if we want to change from sin to cos with keeping positive sign, just add 90, but if we subtract 90 we will get negative cos, isn't it?

[@MichelvanBiezen]

So why does that make anything wrong? sin(x+90) = cos(x) and cos(x-90) = sin(x)

[@mayankkaushik1091]

@@MichelvanBiezen yes sir but still sin(x-90) is -ve cos not +cosine which is not required in our solution

[@eeejobacademy509]

I love this video thank you sir♥

[@arunrawat2142]

Thanks Gurudev🙏🙏❤❤

[@MichelvanBiezen]

You are welcome. 🙂

[@vijaysitarampawar6193]

very good lecture

[@muhammaduzairshafique3587]

I think we should add 90 in sine to convert it into cos.....because sin lags cos by 90

[@toshi2252]

nah, try to calculate on ur calculator

[@lauraciavarella6351]

thanks a lot :so much clear!!!

[@PrinceKumar-cy5ll]

Thanks .. I m from india.

[@MichelvanBiezen]

Welcome to the channel!

[@shubhamtechvideos2280]

Thanks sir

[@raza8442]

Nice

[@rockyamisola7142]

2:40 - 90 cos to sin, +90, sin to cos. Help!

[@piyushkadukar7337]

same here

[@user1638jwiwhwhlnab]

perfect

[@Ehmedbaz]

great

[@MichelvanBiezen]

Glad the videos are helpful. 🙂

[@c.L0UDZ]

W mans

[@MichelvanBiezen]

?

[@curtpiazza1688]

😊

[@MichelvanBiezen]

🙂