# AP Physics 2: 1.2 Fields in Space

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AP Physics 2: 1.2 Fields in Space. What is the magnitude and direction of magnetic field B_{A} at point A?

AP Physics 2 | Fields in Space |

Language | English Language |

Science Practice 6 | Working with scientific explanations and theories |

### Transcript

distance of feet Wire one carries a current of i

sub one and wire to carries a current of ice

up to the current ice of one equals one sixth

of ice up to and the distance labeled x equals

one fourth of the distance D find the magnitude and

direction of the magnetic field Be savaii at point a

and here the potential answer right there First of all

let's figure out the direction of the field A magnetic

field is in three dimensions but the screen were looking

at on Lee has to it's like the page of

a book So to determine how the field is turning

around the wire will use a version of the right

hand room Well look at the wire one first that

current is moving Prop words So with an open hand

we point the thumb of our right hand in the

direction of the current Then we curl our fingers like

we're making a furious physics fist of justice The direction

that our fingers curl is the direction of the field

Conventionally speaking of far fingers curl away from us The

field is said to go into the page If the

fingers curl toward us the field is said to go

out of the page so the field around the first

wire is going into the page for wire to our

thumbs point down And once again our fingers curl away

from us into the page since both fields or going

in the same direction that combined field That point is

also headed into the page so we can already not

answers being deep out of contention And because the fields

generated by each wire are in the same direction we

can add them up to determine the total field at

point a So now if we may let's get ready

for equations Well the equation for magnitude for a magnetic

field is the concept of permeability of free space times

the current over to pi times the radius or the

distance from the wire Well the equation looks like this

Her point a the distance will use for the first

wire is x and we'll use d minus x for

the second wire When we adam together it looks like

this and we could make that a little cleaner So

now our equation is the constant of permeability of free

space over to pi times the sum of current one

over distance x plus current to over distance D minus

x We can sub in the given value of Acts

which was 1 quarter d to give us this equation

And we can make that a little cleaner that way

And we can also swap out current i sub one

for its value in terms of ice Up to the

field at point a equals the concept of permeability of

free space over to pi times distance times the sum

of four Six i sub two plus four thirds aye

sub too And that equals the concept of permeability of

free space Times ice up to over pi times distance

at long last we can definitively say without a doubt

the correct answer is c And after all that well 00:03:08.69 --> [endTime] we've got to go lay down