# Physics hw help me please?

Three infinitely long wires are located at the corners of a square which has a side length of d. (d = 1mm) The wires are perpendicular to the page.

### 1 Answer

- NCSLv 71 month agoFavourite answer
B = 2e-7T·m/A * I / r

with direction given by right hand rule

AT POINT O:

r = d/√2 = 7.07e-4 m

due to I1:

B1 = 2.83e-4 T directed at NW (Θ = 135º)

due to I2:

B2 = 1.98e-3 T directed at NE (Θ = 45º)

due to I3:

B3 = 2.83e-4 T directed at SE (Θ = 45º)

B1 and B3 cancel. So the field at O is

B = B2 = 1.98e-3 T directed NorthEast

AT POINT P:

distance for I2 is d√2

magnitude due to I1 and I3:

|B1| = |B3| = 2e-7T·m/A * 1A / 0.001m = 2e-4 T

B1 is directed North and B3 is directed East.

B2 = 2e-7T·m/A * 7A / 0.001m*√2 = 9.9e-4 T

directed to Northeast

Bx = (9.9*cos45º + 2)*e-4 T = 9e-4 T

By = (9.9*sin45º + 2)*e-4 T = 9e-4 T

B = 1.4e-3 T

directed to NE (45º above "east")

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