QJEEM15Ph3cef: JEE Main 2015 Physics - Class 12 JEEM15Ph3cef Solution: Two long current carrying thin wires, both with current I , are …

Question

Verified Solution • 2025–26 Session moderate

Two long current carrying thin wires, both with current

I,

are held by insulating threads of length

L

and are in equilibrium as shown in the figure, with threads making an angle

^{'} θ^{'}

with the vertical. If wires have mass

λ

per unit-length then the value of

I

is :
(

g =

g r a v i t a t i o n a l

a c c e l e r a t i o n

)

Accepted Answer

Let us consider

^{'} ℓ^{'}

length of current carrying wire,

At equilibrium

T \cos θ = λ g ℓ

and

T \sin θ = \frac{μ_{0}}{2 π} \frac{I \times I l}{2 L \sin θ}

[

as

\frac{F_{B}}{ℓ} = \frac{μ_{0}}{4 π} \frac{2 I \times I}{2 ℓ \sin θ}]

Therefore,

I = 2 \sin θ \sqrt{\frac{π λ g L}{u_{0} \cos θ}}

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