Magnetic force between two currents going in the same direction | Khan Academy

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Sal shows how to determine the magnetic force between two currents going in the same direction. Created by Sal Khan.
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Physics on Khan Academy: Physics is the study of the basic principles that govern the physical world around us. We'll start by looking at motion itself. Then, we'll learn about forces, momentum, energy, and other concepts in lots of different physical situations. To get the most out of physics, you'll need a solid understanding of algebra and a basic understanding of trigonometry.
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[@0rangeflava]

Sal's ability to draw hands is insane

[@saelbennoa6226]

+Daniel Lim IKR, I'm impressed

[@gints2766]

This helps me a lot the night before a test on a subject i wasn't paying attention to. It's the end of the year, Praise Khan Academy!

[@serendipity6720]

So how was the exam? 😅😅Too late?hope you did well 😊

[@gints2766]

@@serendipity6720 wha! That’s from 5 years ago. I don’t remember this at all. But I still don’t pay attention… :>

[@andrewH11123]

I know you say this is basic stuff for high schoolers, but this is appropriate material for a grad admissions test like the MCAT! Very well explained

[@SamIAm9092]

Dude you draw hands SO well

[@mwszmwsz]

Sal, i love how straight you make your lines.

[@funnymemes9736]

Best explanation ever sir! LOVE TO HAVE U AS MY TEACHER😍

[@konkking6127]

your are awesome ... your videos help me very much . so I just wanted to thank you for all ylur effort

[@LadyGagaSweetBaby]

This is SO USEFUL! Thank you

[@pass135]

When you say the direction of the current or the direction of the velocity, is this direction of conventiaonal current or actual flow of electrons?

[@MagicalD7om]

I am confused at defining the direction of force from wire two. Can you explain how can I use my right hand to determine the direction of force? Thank you

[@aaabbb-tr2yd]

The magnetic field B from I2 in the position of wire1 is actually coming out of the screen as per the right hand grip rule. Therefore, the cross product between a charge flow direction and the field B is going to act towards the right of wire1, or, towards wire2. So they wires attract each other due to the current flowing in the same direction.

[@urdouchbag]

@bmgag19 its revolving around the wire....so it has to go into the page at some point and come out of it at another point....i think you have a problem with imagining planes...once you know how to imagine planes..you will get it

[@bmgag19]

I dont understand why B1 goes into the page. I thought it was revolving around the wire.

[@johnbrown1867]

revolving in a circular motion around the wire, coming towards you from left going away on the right in this example. Think of a pipe around the wire moving in a counter clockwise direction, looking from the top down.

[@oindrillamitra3570]

It has helped me a lot..... Thank you.....

[@jpjpjpjpx]

Sal is an artist

[@sahejveer7404]

To find the direction of force we should use left hand rule, why are we using right hand?

[@dipeshtodi]

Tysm ❤️

[@squarkman]

So what if you moved L down on the screen .5 inches. Does this change the equation. Or what if you move it down 2 miles? It seems it's actual position would be important but the actual location along the wire was never discussed. Thx

[@bdd7529]

In his other video he showed that B= (μI)/(2πR). With an increase in R which is the distance separating the wires, the magnitude of the magnetic field B decreases. Since the force F is a function of the magnitude of the magnetic field, 2 miles apart the wires would still attract one another but F would be extremely weak.

[@codingstyle9480]

Something that could be explained in 3-4 minutes is explained in 10 minutes. Calculate the efficiency?

[@varshapaliwal7464]

Sir why we are taking length as a vector

[@NomadicIsaac]

I get the Right Hand Rule now! It makes sense!

[@spaff61]

thank you very much for these videos

[@prateekchauhan732]

how to get tl 85 for windows 7

[@litlwyteguy]

You are the best thing !

[@marvolotom]

are you sure that you dont confuse something with left hand rule? i seriously dont know when to apply left hand rule and when the right hand rule

[@winjaxer]

Can anyone confirm if the magnetic field in between the wires amounts to zero?

[@AryanSingh-my2gt]

Extermely helpful sir

[@saadj3388]

I thought your hand was brown

[@boredpeople100]

these are awesome! =) thank you

[@nikhilsomvanshi9960]

The only thing i could not understand is how you took L(Contextual length of wire) as a vector. I mean how do you put direction to a length? How did we assume the length's direction to be in the direction of the current? Any help on this?

[@playground945]

it’s actually a displacement

[@playground945]

if you know why do they repel or attract each other?

[@scottk224]

can someone please explain to me why L is a vector quantity? I understand mathematically it makes sense to be a vector because it is multiplied by another vector (B) in order to give a third vector in a third dimension (F). However, it represents a distance- how can a distance be a vector quantity? distance has no direction, right?

[@Reydriel]

Actually, it's a displacement. It's derived from the Velocity = Displacement/Time equation :)

[@scottk224]

ah makes sense. thanks so much

[@yusraimran8416]

Why is B2 popping out of the page ?

[@bdd7529]

Yusra Imran Remember the right hand drawn beside L1 showing the direction of the magnetic force around a wire- left to right. As the magnetic field B1 emerging from L1 arrives at L2, it completes a semi-circle and enters the page. On the other hand, the magnetic field B2 from L2 cannot go right to left toward L1 so it arrives at L1 by entering the page, going below the wire and emerging out on the other side where L1 is. Hence B2 comes out of the page.

[@jetpaq]

current wire is gold sal!! JK but I prefer the gold..easier to visualize. Man you are the best !

[@Noelin397]

essence of this class is how to draw shape of right hand perfectly haha

[@abdelrhmanselim8381]

as i know , the right hand used for positive charge particle, the left hand used for negative ,, the current is negative ( electrons) why we used the right hand ??

[@JohaerJilani]

Abdelrhman selim electrons act opposite, same with electrostatics

[@khaledyasser8293]

He is using conventional notation where it's positive charges flowing through wires. Imagine it was negative charges but the direction reversed

[@AceAites]

Why are your hands so interesting to look at?

[@icaptureditforyou]

*Counterclockwise from the Top *Clockwise from the Bottom

[@JohnSmith-ns8ni]

How is length a vector?

[@awais8451]

when length is taken in terms of displacement then it becomes vectors as shown

[@paviWasHere]

I love sal

[@himesharora4417]

plz sr take as much time u want bt go complicated

[@jamesusespivot]

Only 24 secobd into the vid. Solely based on the fact that electrostatic and magnetic forces are the same thing. I think the two wires would repel because in terms of electrostatic they would repel

[@johnbrown1867]

i think its because opposite fields attract like north south on a magnet.

[@MrX-tc7ov]

Mu Knot lOoKs fAncY

[@rachaelybarra3698]

why does L2 go up again?

[@jangabiolaedu]

what's gonna happen if current 2 is opposite direction?

[@neelamroy7467]

the would move apart

[@bellasinfonia]

side note… you draw really good hands LOL

[@kulkid40]

"Current Carrying Wire"

[@vannanilavan1927]

You rock

[@jamesusespivot]

6:05 into the video. I predict I was wrong

[@hamzie11]

Good try

[@rothr92]

But its exactly the same thing....

[@anoychowdhury566]

09:47 lol hahahahaha

[@PrashantMohta]

cross product , by product , i see what you did there ;D

[@saifullahrahman]

the hand i draw looks like a potato

[@drewpierpont3361]

Sal sounds like he has a cold here.

[@MURCH9876]

They aren't that great.

[@digvijaysingh6113]

Ur way of teaching on computer is not very good instead you should use paper and pen. I m sure it will be a lot better.

[@بودكاستفولوتميس-ن1ج]

Tbh I'm finding it difficult to understand your video