Circuits question, series vs parallel

[Falcon99]

Homework Statement

There are 2 circuits.
A:
-A series circuit
Components:
-Motor
-Filament lamp
-Resistor

B:
-A parallel circuit
Components:
-Motor
-Filament lamp
-Resistor
-Each component is in a separate parallel circuit

Question)Explain why the power of the motor is lower in the circuit shown in A than the circuit shown in B.

Homework Equations

V=IR
P=VI
P=I^2R
[/B]

The Attempt at a Solution

My solution of to why circuit A has a lower power is because of the fact that we have less pd as voltage is shared out but current stays constant P=VI ,we would also know that resistance is cumualtive and so would decrease total power as P=I^2R . However in circuit B it is parallel and so current is shared out and voltage stays constant P=VI, but in parallel resistance decreases as more resistance is added ,so by P=I^2R circuit B has more power . Is this a strong enough explanation for the question?[/B]

 

[Let'sthink]

Homework Statement

There are 2 circuits.
A:
-A series circuit
Components:
-Motor
-Filament lamp
-Resistor

B:
-A parallel circuit
Components:
-Motor
-Filament lamp
-Resistor
-Each component is in a separate parallel circuit

Question)Explain why the power of the motor is lower in the circuit shown in A than the circuit shown in B.

Homework Equations

V=IR
P=VI
P=I^2R
[/B]

The Attempt at a Solution

My solution of to why circuit A has a lower power is because of the fact that we have less pd as voltage is shared out but current stays constant P=VI ,we would also know that resistance is cumualtive and so would decrease total power as P=I^2R . However in circuit B it is parallel and so current is shared out and voltage stays constant P=VI, but in parallel resistance decreases as more resistance is added ,so by P=I^2R circuit B has more power . Is this a strong enough explanation for the question?[/B]

 

[Let'sthink]

Better to use P = V^2/Req.

 

[NFuller]

Is this a strong enough explanation for the question?

I would say no. The explanation is not very consistent and you have random formulas interjected into sentences that do not justify the claims you are making. For example what is $R$ in the equations? Is it the resistance of the light bulb, the motor, or the whole circuit?

I would suggest that you actually find a mathematical expression for the power dissipated by the motor in each circuit and show that one is less than the other.

 

[Let'sthink]

Better to use P = V^2/Req.

Sorry, the correct equation is P = V^2/(2Req)

 

[Chandra Prayaga]

I would suggest that you should not look for a formula. Draw the circuit diagram for each case, use standard rules of circuits to find the current in the motor, then use the formula for the power in the motor, and then compare the two. Using a formula to start with is never a good idea.