question_answer

Two concentric coils each of radius equal to\[2\pi \]cm are placed at right angles to each other. 3 A and 4 A are the currents flowing in each coil respectively. The magnetic induction in \[Wb/{{m}^{2}}\]at the centre   of   the   coils , will   be \[({{\mu }_{0}}=4\pi \times {{10}^{-7}}Wb/Am)\]     AIEEE  Solved  Paper-2005

A) \[12\times {{10}^{-5}}\]               

B)        \[{{10}^{-5}}\]                  

C)        \[5\times {{10}^{-5}}\]                  

D)        \[7\times {{10}^{-5}}\]

Correct Answer: C

Solution :

The magnetic field induction at centre O due to circular current, \[{{B}_{P}}\,=\frac{{{\mu }_{0}}}{2}\,\frac{{{l}_{2}}}{R}\,=\frac{4\pi \times {{10}^{-7}}\times 4}{2\times 0.02\,\pi }\,\] and magnetic field induction at the centre due to circular current , Net magnetic field induction it the centre due to both the circular currentsand