Power Loss

hi,

let us assume a circuit with two DC supplies of 5V and 3V, and a resistor of 1k in series with one another. Also 5V and 3V are opposing one another.

Now the power loss across the resistor is I*I*R. = 4mW.
The question is, will there be any power loss across the 3V DC supply?
I feel there won't be any power loss across 3V supply.

I have attached the circuit.

It's a really confusingly drawn circuit - but the 5V battery will charge the 3V one, until both batteries are equalised.

Yes, the 3 volt battery will dissipate .006 watts (3 volts * .002 amps). The resister would dissipate .008 watts (2 volts * .002 amps).

If you don't believe them, maybe you will believe the simulator: The 5V battery delivers 10mW, the 3V battery dissipates 6mW, and the resistor dissipates 4mW. Note that the power delivered = the power dissipated. Technically, depending on the battery chemistry, some of the power going into the 3V battery may be charging it, rather than just raising its temperature.