As the leading power factor of the load of an alternator decreases, the magnitude of generated voltage required to give rated terminal voltage ______________.

The correct answer is option 2.
Explaination:-

• As the leading power factor of the load of an alternator decreases, the magnitude of the generated voltage required to give the rated terminal voltage increases.
• This happens because a leading power factor causes the terminal voltage to rise, and to maintain the rated terminal voltage, the excitation (generated voltage) must be adjusted accordingly.

Additional Information There are three causes of voltage drop in the alternator.

• Armature circuit voltage drop
• Armature reactance
• Armature reaction

The first two factors always tend to reduce the generated voltage, and the third factor may tend to increase or decrease the generated voltage. The nature of the load affects the voltage regulation of the alternator.

•  At unity and lagging power factor loads, the terminal voltage is always less than the induced EMF and the voltage regulation is positive.
• At higher leading loads, the terminal voltage is greater than the induced EMF and the voltage regulation is negative.
• The lower the leading power factor, the greater the voltage rise from no load (E_o) to full load (V_t).
• The lower the lagging power factor, the greater the voltage decrease from no load (E_g) to full load (V_t).

Nature of armature reaction on alternator