Vector Fields

Published On :2021-11-11 01:40:00

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 Vector Fields

Definition   A vector field is a function F that assign to point whether it's in two dimension or three dimension 
the best way to understand the vector fields is by drawing it
and we have a special notations for vector fields 
F(x,y,z)=Q(x,y,z) i+ P(x,y,z) j+ R(x,y,z) k
or
F(x,y,z)=<Q(x,y,z)P(x,y,z)R(x,y,z)>


For Example:[( - 1,1) to ,,, < 1, - 1 > ]
this directional line will start at point (-1,1) and it will move 1 unit to write and 1 unit down
                                             



Important notes to remember:

Position vector is a vector from the origin to a point, so it’s like a radius of the circle that centered at the origin.
If the dot product equal zero then two vectors is perpendicular to each other.



Example 2    A vector field on R is defined by {bf{F}}(x,y) =  - y,{bf{i}} + x,{bf{j}}. Describe F by sketching some of the vectors F(x,y)

Solution: 

 

 

 

 

 

 

 



the lines appears like tangents of a circles
what is the dot product of our vector field with the position vector?
{bf{x}}, cdot ,{bf{F}}({bf{x}}) = (x,{bf{i}}, + ,y,{bf{j}}) cdot ,( - y,{bf{i}} + x,{bf{j}}) =  - x,y + y,x = 0
this shows they are perpendicular to each other therefore tangent to a circle with center the origin