\(N =1\)
For \(ABCD\)
\(\overrightarrow{ M }_{1}= abI \hat{ K }\)
For \(DEFA\)
\(\overrightarrow{ M }_{2}= abI \hat{ j }\)
\(\overrightarrow{ M }=\overrightarrow{ M }_{1}+\overrightarrow{ M }_{2}\)
\(=\operatorname{ab} I (\hat{ k }+\hat{j})\)
\(=\operatorname{ab} I \sqrt{2}\left(\frac{\hat{j}}{\sqrt{2}}+\frac{\hat{ k }}{\sqrt{2}}\right)\)