question_answer

A solenoid of 0.4 m length with 500 turns carries a current of 3 A. A coil of 10 turnsand of radius 0.01 m carries a current of 0.4 A. The torque required to hold the coil with its axis at right angle to that of solenoid in the middle part of it, is

A)  \[6{{\pi }^{2}}\times {{10}^{-7}}N\,\,\,m\]

B)  \[3{{\pi }^{2}}\times {{10}^{-7}}N\,\,\,m\]

C)  \[9{{\pi }^{2}}\times {{10}^{-7}}N\,\,\,m\]

D)  \[12{{\pi }^{2}}\times {{10}^{-7}}N\,\,\,m\]