The correct answer is: D. Magnetization characteristic = external characteristic
The magnetization characteristic of a DC generator is the relationship between the field current and the generated voltage. The external characteristic of a DC generator is the relationship between the terminal voltage and the load current.
The magnetization characteristic is a straight line with a positive slope. The external characteristic is a curve with a negative slope. The intersection of the two curves is the no-load point.
The armature reaction is the effect of the armature current on the magnetic field of the generator. The armature reaction causes the generated voltage to decrease at high loads.
The ohmic drop is the voltage drop in the armature windings. The ohmic drop causes the terminal voltage to decrease at high loads.
The following is a brief explanation of each option:
- Option A: External resistance = internal characteristic armature reaction. This is not correct because the external resistance is not equal to the internal characteristic armature reaction. The external resistance is the resistance of the load, while the internal characteristic armature reaction is the effect of the armature current on the magnetic field of the generator.
- Option B: Internal characteristic = magnetization characteristic ohmic drop. This is not correct because the internal characteristic is not equal to the magnetization characteristic ohmic drop. The internal characteristic is the relationship between the field current and the generated voltage, while the magnetization characteristic ohmic drop is the voltage drop in the field windings.
- Option C: External characteristic = magnetization characteristic ohmic drop armature reaction. This is not correct because the external characteristic is not equal to the magnetization characteristic ohmic drop armature reaction. The external characteristic is the relationship between the terminal voltage and the load current, while the magnetization characteristic ohmic drop armature reaction is the effect of the armature current on the magnetic field of the generator and the ohmic drop in the armature windings.
- Option D: Magnetization characteristic = external characteristic. This is correct because the magnetization characteristic is the relationship between the field current and the generated voltage, while the external characteristic is the relationship between the terminal voltage and the load current.