Answer:
The emf in the inductor continues to be zero.
Step-by-step explanation:
It is given that, an inductor with no resistance carries a constant current. Then the current is brought to a new constant value twice as large. Finally, the current is constant at its higher value. We know that the voltage across the inductor is given by :
is the change in current
Since, the change in current is constant, then the emf in the inductor continues to be zero. So, the correct option is (A).