Question

Two, long, straight direction as shown. wires separated by 0.40 cm carry the same current I = 3 A in the same direction as shown. Are the wires attracted or repulsed (circle one) from each other? What is the magnitude and direction of the magnetic field at point P? What is the magnitude and direction of the magnetic field at point S?

Answer 1

(a) Since the two wires carry current in same direction, they attract each other (the magnetic fields produced by these current will point in opposite directions. As a result the two wires attract each other)

(b) Magnetic field due to wire at a distance of 7cm is

                                                     $B_1 = \frac{\mu _0i}{2\pi r} =\frac{4\pi *10^{-7}*3}{2\pi *0.07}=85.71*10^{-7}\:T$

Magnetic field due to wire at a distance of 4cm is

                                                     $B_2 = \frac{\mu _0i}{2\pi r} =\frac{4\pi *10^{-7}*3}{2\pi *0.04}=150*10^{-7}\:T$

Total Magnetic field at Point P is = B1+B2 = 235.71*10^{-7} T

(b) using Pythogoras theorem,

          the first wire(first circled one) is at a distance of $\sqrt{3^2+4^2}$ = 5 cm = 0.05 m

    Magnetic field due to wire at a distance of 5cm is

                                                     $B_1 = \frac{\mu _0i}{2\pi r} =\frac{4\pi *10^{-7}*3}{2\pi *0.05}=120*10^{-7}\:T$

Magnetic field due to wire at a distance of 4cm is

                                                     $B_2 = \frac{\mu _0i}{2\pi r} =\frac{4\pi *10^{-7}*3}{2\pi *0.04}=150*10^{-7}\:T$

B2 3, уст 9 3,Sine 2. 3 3cm 3 tan 53-130 Magneic Held 120 x10 coS 5330e Sin 53 130A