Question

A long horizontal straight wire \(P\) carrying a current of \(120\,\mathrm{A}\) is fixed and another horizontal straight wire \(Q\) of linear mass density \(1.2\times10^{-2}\,\mathrm{kg\,m^{-1}}\) is placed \(2.5\,\mathrm{cm}\) below wire \(P\). If wire \(Q\) remains suspended in equilibrium in air, then the current through it is \[ \left(g=10\,\mathrm{m\,s^{-2}}\right) \]

• A. \(225\,\mathrm{A}\)
• B. \(75\,\mathrm{A}\)
• C. \(250\,\mathrm{A}\)
• D. \(125\,\mathrm{A}\)

Hint:

For two long parallel wires, \[ \boxed{ \frac{F}{L} = \frac{\mu_0 I_1 I_2}{2\pi d} } \] For equilibrium, \[ \boxed{ \frac{F}{L} = \lambda g. } \]

Answer 1

The Correct Option is D