In the given figure the magnetic flux through the loop increases according to the relation $\phi _ { B } ( t ) = 10 t ^ { 2 } + 20 t$, where $\phi _ { B }$ is in milliwebers and $t$ is in seconds. The magnitude of current through $R = 2 \Omega$ resistor at $t = 5 \mathrm {~s}$ is $\_\_\_\_$ mA.