DC generator , the generated emf at load is less than that at no-load due to:*Voltage dropArmature reactionInterpolesArmature resistance

The generated EMF (Electromotive Force) at load in a DC generator is less than that at no-load due to several reasons:

1. Voltage Drop: When the generator is under load, the current through the armature increases. This increased current causes a voltage drop across the armature resistance, which reduces the net output voltage.

2. Armature Reaction: The magnetic field produced by the current in the armature windings can distort the main magnetic field of the generator. This distortion, known as armature reaction, can reduce the net magnetic field and thus the generated EMF.

3. Interpoles: Interpoles are small poles placed between the main poles to counteract the effect of armature reaction. However, they can also cause a small voltage drop, reducing the generated EMF.

4. Armature Resistance: The resistance of the armature windings causes a voltage drop across them when current flows. This reduces the net output voltage of the generator.

So, all these factors contribute to the reduction of the generated EMF at load in a DC generator.