What is the magnetic field strength at point a? B= ???? What is the direction of the magnetic field strength at point a? - to the left

Magnetic field at a point due to a current carrying wire is given by :

B = uI/(2*pi*r)

where u = 1.26*10^-6

I = current

r = distance from the wire

So, magnetic field at a due to (upper wire), B1 = u*(I)/(2*pi*0.02) directed out of the plane

NOTE:--> distance of point a from upper wire = 2 cm = 0.02 m and I = 15 A

Similarly for lower wire, B2 = u*(I)/(2*pi*0.06) directed into the plane

So, net magnetic field at point a , Bnet = B1-B2 <----- as directions are opposite so subtraction

So, Bnet = u*(I)/(2*pi*0.02) - u*(I)/(2*pi*0.06)  

= 1.26*10^-6*15/(2*pi*0.02) -1.26*10^-6*15/(2*pi*0.06)

= 1*10^-4 T <------------answer

Direction is out of the page as B1 is greater than B2 <---------answer

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For point b

B1 = 1.26*10^-6*15/(2*pi*0.02) into the page

B2 =  1.26*10^-6*15/(2*pi*0.02) into the page

So, Bnet = B1 + B2 <---- both are directed in same direction

So, Bnet = 3*10^-4 T <-----------answer

Direction = into the page <-----------answer

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For point c,

Bnet = 1*10^-4 T

Direction = out of the page