Well, for measuring DC watt, basically we use a shunt resistor. Current go through this shunt resistor and develop a tiny voltage drop and amplified by the op-amp. But, how the amplified voltage value is used to measure the power across the load? Thanks.

 

We multiply the value representing current by the applied circuit voltage.

 

We multiply the value representing current by the applied circuit voltage.

am i correct:
value representing current = current across shunt.
applied circuit voltage = voltage across the load?

 

am i correct:
value representing current = current across shunt.

Actually, value representing current = current thru shunt (load current), current thru meter proportional to voltage drop across shunt but calliberated to record load current!

applied circuit voltage = voltage across the load?

You are correct!