In the figure shown there are two semicircles of radii \[{{r}_{1}}\] and \[{{r}_{2}}\] in which a current i is flowing. The magnetic induction at the centre O will be

\[\frac{{{\mu }_{0}}i}{4}\left( \frac{{{r}_{2}}-{{r}_{1}}}{{{r}_{1}}{{r}_{2}}} \right)\]

\[\frac{{{\mu }_{0}}i}{r}({{r}_{1}}+{{r}_{2}})\]

\[\frac{{{\mu }_{0}}i}{4}({{r}_{1}}-{{r}_{2}})\]

\[\frac{{{\mu }_{0}}i}{4}\left( \frac{{{r}_{1}}+{{r}_{2}}}{{{r}_{1}}{{r}_{2}}} \right)\]

In the figure shown there are two semicircles of radii \[{{r}_{1}}\] a

1.	In the figure shown there are two semicircles of radii \[{{r}_{1}}\] and \[{{r}_{2}}\] in which a current i is flowing. The magnetic induction at the centre O will be
A.	\[\frac{{{\mu }_{0}}i}{r}({{r}_{1}}+{{r}_{2}})\]
B.	\[\frac{{{\mu }_{0}}i}{4}({{r}_{1}}-{{r}_{2}})\]
C.	\[\frac{{{\mu }_{0}}i}{4}\left( \frac{{{r}_{1}}+{{r}_{2}}}{{{r}_{1}}{{r}_{2}}} \right)\]
D.	\[\frac{{{\mu }_{0}}i}{4}\left( \frac{{{r}_{2}}-{{r}_{1}}}{{{r}_{1}}{{r}_{2}}} \right)\]
Answer» D. \[\frac{{{\mu }_{0}}i}{4}\left( \frac{{{r}_{2}}-{{r}_{1}}}{{{r}_{1}}{{r}_{2}}} \right)\]