Let $\vec{a}=\hat{i}+2 \hat{j}+\lambda \hat{k}, \vec{b}=3 \hat{i}-5 \hat{j}-\lambda \hat{k}, \vec{a} \cdot \vec{c}=7,2 \vec{b} \cdot \vec{c}+43=0, \vec{a} \times \vec{c}=\vec{b} \times \vec{c}$. Then $|\vec{a} \cdot \vec{b}|$ is equal to
Magnetic flux (in weber) in a closed circuit of resistance $20 \,\Omega$ varies with time $t ( s )$ as $\phi=8 t^2-9 t+5$. The magnitude of the induced current at $t =0.25\, s$ will be ______$mA$