$\overline{E}=\frac{\left| \Delta \Phi  \right|}{\Delta t}=\frac{\left| {{\Phi }_{2}}-{{\Phi }_{1}} \right|}{\Delta t}=\frac{\left| {{B}_{2}}A\operatorname{Cos}\theta -{{B}_{1}}A\operatorname{Cos}\theta  \right|}{\Delta t}=\frac{\left| A\operatorname{Cos}\theta ({{B}_{2}}-{{B}_{1}}) \right|}{\Delta t}=\left| A\operatorname{Cos}\theta \frac{\Delta B}{\Delta t} \right|$ $\Rightarrow \left| \overline{E} \right|=(200\times {{10}^{-4}})\times 1\times 40=0/8V$