AP Physics 2 : Circuit Power

Study concepts, example questions & explanations for AP Physics 2

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Example Questions

Example Question #11 : Circuit Power

3 sets of parallel resistors

Calculate the power being dissipated by

Possible Answers:

None of these

Correct answer:

Explanation:

The first step is to find the total resistance of the circuit.

In order to find the total resistance of the circuit, it is required to combine all of the parallel resistors first, then add them together as resistors in series.

Combine  with with with .

 

Then, combining  with  and :

Ohms is used law to determine the total current of the circuit

Combing all voltage sources for the total voltage.

 

Plugging in given values,

 

 

It is true that the voltage drop across parallel resistors must be the same, so:

Using ohms law:

 

It is also true that:

Using Subsitution:

Solving for :

Pluggin in values:

 

 Using the definition of electric power, where  is current and is the resistance of the component in question.

Example Question #81 : Circuits

3 sets of parallel resistors

Calculate the power being dissipated by

Possible Answers:

None of these

Correct answer:

Explanation:

The first step is to find the total resistance of the circuit.

In order to find the total resistance of the circuit, it is required to combine all of the parallel resistors first, then add them together as resistors in series.

Combine  with with with .

 

Then, combining  with  and :

Ohms is used law to determine the total current of the circuit

Combing all voltage sources for the total voltage.

 

Plugging in given values,

 

 

It is true that the voltage drop across parallel resistors must be the same, so:

Using ohms law

 

It is also true that:

 

 Using Subsitution:

 

 Solving for :

 

 Plugging in values:

 

 Using the definition of electrical power, where is current and is the resistance of the component in question.

 

Example Question #13 : Circuit Power

3 sets of parallel resistors

Calculate the power being dissipated by

Possible Answers:

None of these

Correct answer:

Explanation:

The first step is to find the total resistance of the circuit.

In order to find the total resistance of the circuit, it is required to combine all of the parallel resistors first, then add them together as resistors in series.

Combine  with with with .

 

Then, combining  with  and :

Ohms is used law to determine the total current of the circuit

Combing all voltage sources for the total voltage.

 

Plugging in given values,

 

 

It is true that the voltage drop across parallel resistors must be the same, so:

Using ohms law

 

It is also true that:

 

 Using Subsitution:

 Solving for :

 

Pluggin in values:

 

Using the definition of electrical power, where is current and is the resistance of the component in question:

Example Question #14 : Circuit Power

Three parallel resistors

What is the power being dissapaited by ?

Possible Answers:

None of these

Correct answer:

Explanation:

, , and are in parallel, so they are added by using:

Plugging in given values:

, , and  are in series. So they are added conventionally:

Plugging in values:

First, it is necessary to find the total current of the circuit. Using Ohm's law:

 

Solving for :

The total current of the circuit is also the current through

 Using the definition of electric power, where is current and is the resistance of the component in question:

 

Example Question #91 : Circuit Properties

Three parallel resistors

What is the power being dissapaited by ?

Possible Answers:

None of these

Correct answer:

Explanation:

, , and are in parallel, so they are added by using:

Plugging in given values:

, , and  are in series. So they are added conventionally:

Plugging in values:

First, it is necessary to find the total current of the circuit. Using Ohm's law:

 

Solving for :

Because and  are in parallel,

Also, the voltage drop must be the same across all three since they are in parallel.

Using Ohm's law again and substituting:

Using algebraic subsitution:

Solving for :

Plugging in values:

 

 Using the definition of electric power, where is current and is reistance.

 

Example Question #92 : Circuit Properties

Three parallel resistors

What is the power being dissapaited by ?

Possible Answers:

None of these

Correct answer:

Explanation:

, , and are in parallel, so they are added by using:

Plugging in given values:

, , and  are in series. So they are added conventionally:

Plugging in values:

First, it is necessary to find the total current of the circuit. Using Ohm's law:

 

Solving for :

Because and  are in parallel,

Also, the voltage drop must be the same across all three since they are in parallel.

Using Ohm's law again and substituting:

Using algebraic subsitution:

Solving for

 

 Plugging in values:

 

 Using the definition of electrical power, where is the current and is the resistance of the component in question:

 

Example Question #93 : Circuit Properties

Three parallel resistors

What is the power being dissapaited by ?

Possible Answers:

None of these

Correct answer:

Explanation:

, , and are in parallel, so they are added by using:

Plugging in given values:

, , and  are in series. So they are added conventionally:

Plugging in values:

First, it is necessary to find the total current of the circuit. Using Ohm's law:

 

Solving for :

Because and  are in parallel,

Also, the voltage drop must be the same across all three since they are in parallel.

Using Ohm's law again and substituting:

Using algebraic subsitution:

Solving for

Plugging in values

Using the definition of electrical power, where is current and is the resistance of the component in question:

 

 Plugging in values

 

Example Question #94 : Circuit Properties

3 sets of parallel resistors

Calculate the power being dissipated by

Possible Answers:

None of these

Correct answer:

Explanation:

The first step is to find the total resistance of the circuit.

In order to find the total resistance of the circuit, it is required to combine all of the parallel resistors first, then add them together as resistors in series.

Combine  with with with .

 

Then, combining  with  and :

Ohms is used law to determine the total current of the circuit

Combing all voltage sources for the total voltage.

 

Plugging in given values,

 

 

 The voltage drop across parallel resistors must be the same, so:

 

Using ohms law:

It is also true that:

Using Subsitution

 

 Solving for :

 

 Plugging in values

 

 Using the definition of electrical power, where is current and is the resistance of the component in question:

Example Question #91 : Circuit Properties

3 sets of parallel resistors

Calculate the power being dissipated by

Possible Answers:

None of these

Correct answer:

Explanation:

The first step is to find the total resistance of the circuit.

In order to find the total resistance of the circuit, it is required to combine all of the parallel resistors first, then add them together as resistors in series.

Combining with with with .

 

Then, combining  with  and :

Ohms is used law to determine the total current of the circuit

Combing all voltage sources for the total voltage.

 

Plugging in given values,

 

 

 The voltage drop across parallel resistors must be the same, so:

 

Using ohms law:

It is also true that:

Using Subsitution

Solving for :

 

Using the definition of electrical power, where is current and is the resistance of the component in question:

Example Question #911 : Ap Physics 2

A single  battery is in series with several Ohmic resistors. How will the power output of the circuit change if a second  battery is added in series?

Possible Answers:

Doubled

Quartered

Tripled

Halved

Quadrupled

Correct answer:

Quadrupled

Explanation:

The power dissipated by the resistor will be

Using Ohm's Law:

And changing the equation to be exclusively in terms of voltage and resistance:

From this, it can be seen that doubling the voltage will quadruple the power.

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