Final answer:
The resistance of a solenoid when 100V DC is applied and a current of 1A flows is 100 ohms. To calculate the magnetic field strength, further information about the number of turns and the length of the solenoid is required.
Step-by-step explanation:
When a 100V DC is applied across a solenoid and a current of 1A flows through it, this implies that the resistance of the solenoid is 100 ohms. The strength of the magnetic field inside the solenoid can be calculated using Ampère's Law or the formula B = μ₀ * (N/L) * I, where B is the magnetic field, μ₀ is the permeability of free space (4π x 10^-7 T·m/A), N is the number of turns, L is the length of the solenoid, and I is the current. The number of turns per unit length (N/L) would need to be known to calculate the exact magnetic field strength.