Final answer:
The minimum allowable amperage from the ground power unit is not specified, but the force exerted by an electrical current in a magnetic field, such as on a light-rail system's DC power line carrying 1000 A at an angle of 30.0°, can be calculated and has real-world implications for the system's stability.
Step-by-step explanation:
The minimum allowable amperage from the ground power unit is not explicitly provided, but to answer a similar question related to electrical concepts and magnetic forces, we can look at a DC power line for a light-rail system. If a DC power line carries 1000 A at an angle of 30.0° to the Earth's 5.00×10-5-T field, the force on a 100-m section of this line can be calculated using the formula for the magnetic force on a current-carrying conductor: F = ILBsinθ, where I is the current, L is the length of the wire, B is the magnetic field strength, and θ is the angle between the wire and the magnetic field.
In real-world applications, this force can present practical concerns, such as the need for securing the power lines firmly to avoid physical displacement and potential disruptions in the power supply to the light-rail system.