Where is the ground in a flashlight circuit? And what does maximum total power mean in a circuit mean?

It doesn't have a ground.

Maximum total power sounds like a specification, the sum of the power dissipations of all the parts in the circuit.

Not a spec I have seen very often.

Series vs parallel? depends on the exact circuit and the part values.

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A flashlight doesn't have a ground. In many circuits the ground is just the common point or reference point in the circuit. The maximum total power is the product of the voltage supplied to the circuit and current drawn by the circuit. In a parallel circuit the loads are connected in parallel, they are all at the same potential. So the load with the smallest resistance draws the most current and uses the most power. The series circuit has all the loads connected in series, they each have the same current flow. The load with the largest resistance has the most voltage dropped across it and since power = volts x current, it will use the most power.

Where is the ground?  There is a long and a short answer to this question.

SHORT ANSWER:
The ground in a flashlight is on the negative terminal of the battery.

LONG ANSWER:
You can choose ground to be anywhere you want it to be and that choice is always a matter of convenience.  If you really wanted to, you could choose ground to be on your forehead.  To understand this you must understand that voltage is always measured between two points.  Never, ever is voltage measured in only one point.  Voltage is defined physically as something between two points.  That is the way it is.

However, it can be convenient to choose a single point in the universe (on your circuit) where the voltage is said to be zero, and that point is called ground.  Then you measure all the voltages on your circuit between wherever and ground.

This way you don't have to specify two points for everything.  You just say, "Oh, this here is 5 volts" when what you really are saying is "Oh, the voltage difference between this point here and ground is 5 volts."  Really, using the ground concept makes life happy, easy, and satisfying.

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Now for this maximum total power thing.  I'm not exactly sure about the context of this question, but I'll take a stab at it.  I'm guessing that this is a phrase read from a datasheet for some component.

Power is defined as energy per time.  So the maximum power is how much energy per time a component can take before it stops working, catches on fire, or some other bad thing happens.  It is important to make sure that you don't exceed the maximum total power of a component unless you want to see fireworks.

It is also important to know that power in electronics can be expressed as power = voltage*current.  So, if you know the current through some component (like a resistor or light bulb) and the voltage across it then you can calculate how much power it is using.  You will need to sit down and do a little pencil work to make sure you are not going to blow your component out of the water with too much power.  That is the way of electronics, I'm afraid.  But, a little pondering and common sense will go a long way.