What is actully drooping in electrical circuits? Voltage,ampere , etc ?

Need more information to answer the question. What kind of problem are you having?

"Drooping" is a new word I never heard used when dealing with electricity.

Do you mean voltage sag?

Voltage can vary and if it goes below a certain tolerance is called sag.

Voltage that rises above a certain tolerance is called swell.

Amperage can vary depending on the load.

Explain what your question is about.

My question was "what is drooping in a simple ac circuit for example : a lamp oprating at 220v ac. when i measure its current in both nutral and phase ampere was same. now i want to ask that, for example 2 ampere go in lamp and 2ampere are coming from lamp then what was used by lam >>>??????????? voltage or ampere????"

Power was used, measured in watts.

Power = Volts times Amps

Using your example, 220 volts times 2 amps = 440 watts of power was used.

The power used was converted into light and heat dissapated from the lamp.