calculation of device consumption

[Kick]

hiii,
How to calculate the device consumption (mA) of a DC circuit?? should i add the power of each device in that circuit?? and why it's mentioning in mA unit ??

 

[jiripolivka]

Each device has either its resistance (resistors) or if it is an active device, you find its current rating in specifications.
Your circuit is a load for its power supply. You must use or make a power supply that can deliver the required current to the circuit while the DC voltage would not drop.
Current in electronic circuits is typically measured in Amperes or milliamperes.