A long solenoid of cross-sectional radius $R$ has a thin insulated wire ring of uniform cross-section tightly put on its winding. The ring is made out of two different materials such that one half of the ring has a resistance $10$ times that of the other half. The magnetic induction produced by the solenoid varies with time as $B = bt$, where $b$ is a constant. The magnitude of the electric field strength in the ring (other than the induced electric field) is