High School Physics : Electricity and Magnetism

Study concepts, example questions & explanations for High School Physics

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Example Questions

Example Question #10 : Circuit Calculations And Concepts

A circuit has a current, , a voltage, , and a resistance, . If the voltage remains constant, but the current is doubled (), what must the new resistance be?

Possible Answers:

There is insufficient information to solve

Correct answer:

Explanation:

To solve this problem, use Ohm's law:

Since we are doubling the current, but the voltage is remaining the same, we can set our old and new equations equal to each other.

We know that the second current is equal to twice the first current.

Use this equation to substitute current into the first equation.

The initial current now cancels out from both sides.

Divide both sides by two to isolate the final resistance variable.

 

Example Question #11 : Electric Circuits

Ohm's Law describes the relationship between which variables?

Possible Answers:

Voltage, current, resistance

Electric field, current, power

Power, resistivity, electromotive force

Voltage, electric field, power

Resistance, power, electromotive force

Correct answer:

Voltage, current, resistance

Explanation:

Ohm's law can be written as:

It demonstrates that voltage is equal to the product of current and resistance within an electric circuit.

Example Question #12 : Electric Circuits

The current in a circuit is  and the voltage is . What is the resistance?

Possible Answers:

Correct answer:

Explanation:

Ohm's law says . Plug in our given values to solve.

Example Question #13 : Electric Circuits

What is the current of a circuit with a voltage of  and a total resistance of ?

 

Possible Answers:

Correct answer:

Explanation:

For this problem, use Ohm's law: . In this equation  is the voltage,  is the current, and  is the resistance.

We can re-arrange the equation to solve specifically for .

Plug in the given values for voltage and resistance to solve for the current.

 

 

 

 

Example Question #14 : Electric Circuits

What is the resistance in a circuit with a voltage of  and a current of ?

 

Possible Answers:

Correct answer:

Explanation:

For this problem, use Ohm's law:  . In this equation  is the voltage,  is the current, and  is the resistance.

We can re-arrange the equation to solve specifically for .

 

Plug in the given values for voltage and current and solve for resistance.

 

Example Question #15 : Electric Circuits

What is the voltage of a circuit with  of current and  of resistance? 

Possible Answers:

Correct answer:

Explanation:

For this problem, use Ohm's law: . In this equation  is the voltage,  is the current, and  is the resistance.

 

Plug in the given values and solve for the voltage.

 

 

Example Question #16 : Electric Circuits

Ohm's Law describes the relationship between which variables?

Possible Answers:

Power, resistivity, electromotive force

Voltage, electric field, power

Electric field, current, power

Voltage, current, resistance

Resistance, power, electromotive force

Correct answer:

Voltage, current, resistance

Explanation:

Ohm's law can be written as:

 

 

It demonstrates that voltage is equal to the product of current and resistance within an electric circuit.

 

Example Question #17 : Electric Circuits

A circuit has a current, , a voltage, , and a resistance, . If the voltage remains constant, but the current is doubled (), what must the new resistance be?

Possible Answers:

There is insufficient information to solve

 

Correct answer:

Explanation:

To solve this problem, use Ohm's law:

 

Since we are doubling the current, but the voltage is remaining the same, we can set our old and new equations equal to each other.

 

We know that the second current is equal to twice the first current.

 

Use this equation to substitute current into the first equation.

 

The initial current now cancels out from both sides.

 

Divide both sides by two to isolate the final resistance variable.

 

Example Question #1 : Calculating Circuit Power

What is the power of a circuit with a current of  and a resistance of ?

Possible Answers:

Correct answer:

Explanation:

The standard equation for power is:

 

We are given only current and reistance, meaning we must manipulate this equation so that only those variables are present. To do this, we can substitute Ohm's law for voltage.

Now we have an equation for power that uses only current and resistance. Plug in the values given in the question to find the final answer.

Example Question #1 : Understanding Series And Parallel

Each branch of a parallel circuit carries an equal __________.

Possible Answers:

voltage

power

resistance

capacitance

current

Correct answer:

voltage

Explanation:

By definition, each branch of a parallel circuit will have the same voltage. The current, however, may be split between branches in inequal amounts. In contrast, a series circuit will carry a constant current throughout the circuit, but voltage may differ between elements.

Resistance and capacitance are dependent on the elements present in a given circuit, so no claims can be made. Power is similarly dependent on the elements present in a specific circuit.

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