The correct answer is: C. Constant current as well as constant voltage
An amplidyne is a type of motor-generator set that can provide both constant current and constant voltage. It is a DC machine that uses a field winding to create a magnetic field, which in turn induces a voltage in the armature winding. The armature winding is connected to a load, and the current through the load is controlled by the field current. By adjusting the field current, the amplidyne can be made to provide either constant current or constant voltage.
Constant current is important in applications where the load must be driven at a constant speed, such as in conveyor systems. Constant voltage is important in applications where the load must be driven at a constant power, such as in welding machines.
Option A is incorrect because an amplidyne cannot provide constant current if the load resistance changes. Option B is incorrect because an amplidyne cannot provide constant voltage if the load resistance changes. Option D is incorrect because an amplidyne cannot provide constant current, constant voltage, and constant power at the same time. Option E is incorrect because an amplidyne can provide constant current as well as constant voltage.