Hello,
we often consider a resistance as a load,for any device in electrical terms ,
why we need to consider it as resistance/impedance always,because power gets dissipated in resistor and it go waste as heat?
even in antennas we consider its equivalent as a resistor.

 

If we don't consider resistance or impedance, what else would we consider? Capacitance? The load you're putting into a power supply, somehow it will make some work. Put load's equivalent resistance is the method we found of saying this will do work. Not necessarily and relevant, the majority of apparatus you will connect to the power source has a resistance (even copper wires), and doesn't need to be a resistor, unless you're at a very very low temperature.

Hope this helps.

 

Hello,
we often consider a resistance as a load,for any device in electrical terms ,
why we need to consider it as resistance/impedance always,because power gets dissipated in resistor and it go waste as heat?
even in antennas we consider its equivalent as a resistor.

Eh?

It is the other way around: we often consider a load as a resistance

 

The resistive part of the load absorbs the real power (the resistive part can be an actual resistor or appear in the load such as an antenna or motor). The reactance (cause by inductance and/or capacitance) is what determines the reactive part of the load (no real power dissipated).

 

even a perfectly matched antenna has IR lossses. and does cause heating. the mismatch impedance causes heating in the generator. a good match (non reactive) is still current, voltage, and resistance, will heat the load.

 

Thank you,
can any one tell me on what factors we consider load value and place it in all electrical equivalent circuit for analysis.(please do not explain all math stuff)