A very long straight wire carrying an electric current is perpendicular to the x

Question

A very long straight wire carrying an electric current is perpendicular to the x-y plane. The current has a value of 28.3 A and is directed in the -z (into the page). At point 'p', the magnetic field B is represented by one of the arrows. Image here: http://s1148.photobucket.com/albums/o575/sarahjoy1216/?action=view&current;=Screenshot2012-07-14at95015AM.png a)Indicate the direction of the magnetic field at point 'p'. b)Calculate the magnitude of the B-field at 'p'. c)Calculate the x-component of the B-field at 'p'.

Explanation / Answer

a) The position vector(r) of P from wire is -i-4j.
The magnetic field at P will be in the direction idl X r .. i.e., perpendicular to r vector in XY plane (alongside T, in diagram).
b) B = * i/2d = 4*10-7*28.3/(2*17)
=> B = 1.3737 T
c) Doing the dot product with i, wil give the magnetic field.
Let us find unit vector perp to r vector.
I.e., ai+bj be unit vector => (ai+bj).(-i-4j) = 0
=> We get a=-4/17 and b = 1/17

Hence, B vector = 1.3737(-0.97i+0.24j)

So Bx = B.i = 1.3737*0.97 = 1.3325 T

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---