Circuits question, series vs parallel

In summary, the circuits have different powers because the voltage is shared out in A but current is constant in B.
  • #1
Falcon99
8
1

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]
 
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  • #2
Falcon99 said:

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]
 
  • #3
Better to use P = V^2/Req.
 
  • #4
Falcon99 said:
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.
 
  • #5
Let'sthink said:
Better to use P = V^2/Req.
Sorry, the correct equation is P = V^2/(2Req)
 
  • #6
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.
 

Related to Circuits question, series vs parallel

1. What is the difference between series and parallel circuits?

In a series circuit, all components are connected in a single loop, while in a parallel circuit, components are connected in separate paths. This results in different properties such as voltage and current distribution.

2. Which type of circuit is more commonly used in household wiring?

Parallel circuits are more commonly used in household wiring because they allow appliances to operate independently without affecting each other.

3. How does the total resistance of a series circuit compare to a parallel circuit?

In a series circuit, the total resistance is equal to the sum of individual resistances, while in a parallel circuit, the total resistance is less than the smallest individual resistance.

4. Which type of circuit is more reliable?

Parallel circuits are generally considered more reliable because if one component fails, the rest of the circuit can still operate.

5. Can series and parallel circuits be combined?

Yes, it is possible to have a combination of series and parallel circuits within a larger circuit. This is known as a series-parallel circuit and is commonly used in electrical systems.

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