Final answer:
The magnetic field strength in the region 0 < r < R1 of the long, hollow wire is zero.
Step-by-step explanation:
To find the magnetic field strength in the region 0 < r < R1, we can use Ampere's law. Ampere's law states that the line integral of the magnetic field B around a closed loop is equal to the product of the current inside the loop and the permeability of free space.
If the wire carries current I uniformly distributed across its area, then we can consider a circular loop with radius r. For r < R1, the current enclosed by the loop is zero, so the line integral of the magnetic field is also zero. Therefore, the magnetic field strength in this region is zero.