Q.

A rectangular conducting loop of length 4 cm and width 2 cm is in the xy-plane, as shown in the figure. It is being moved away from a thin and long conducting wire along the direction 32x^+12y^ with a constant speed v. The wire is carrying a steady current I=10 A in the positive x-direction. A current of 10 μA flows through the loop when it is at a distance d=4 cm from the wire. If the resistance of the loop is 0.1 Ω, then the value of v is ______ ms-1.

[Given: The permeability of free space μ0=4π×10-7 N A-2]                  [2023]


Ans.

(4)

 Here e.m.f., ε=(B1-B2)bvy

Current, i=εR=μ0I2πR(1d-1d+a)bvy

⇒10-5=2×10-7×100.1[14-18]×2·vy

[Given: I=10 A, R=0.1 Ω, i=10 μA=10-5 A]

∴ vy=2

tanθ=vyvx⇒13=2vx

∴ vx=23

∴ v=vx2+vy2=(23)2+(2)2

        =16=4 ms-1