High School Physics : Electricity and Magnetism

Study concepts, example questions & explanations for High School Physics

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Example Questions

Example Question #3 : Calculating Total Capacitance

Three capacitors, each with a capacity of  are arranged in parallel. What is the total capacitance of this circuit?

Possible Answers:

Correct answer:

Explanation:

The formula for capacitors in parallel is:

Our three capacitors all have equal capacitance values. We can simply add them together to find the total capacitance.

Example Question #4 : Calculating Total Capacitance

What is the total capacitance of a series circuit with capacitors of , and ?

Possible Answers:

Correct answer:

Explanation:

The total capacitance of a series circuit is 

Plug in our given values.

Example Question #5 : Calculating Total Capacitance

Calculate the total capacitance of a circuit with the following three capacitors in parallel.

Possible Answers:

Correct answer:

Explanation:

To calculate the total capacitance for capacitors in parallel, simply sum the value of each individual capacitor.

Example Question #6 : Calculating Total Capacitance

Calculate the total capacitance of a circuit with the following three capacitors in series.

Possible Answers:

Correct answer:

Explanation:

To find the total capacitance for capacitors in series, we must sum the inverse of each individual capacitance and take the reciprocal of the result.

Remember, you must still take the final reciprocal!

Example Question #1 : Using Capacitor Equations

Three capacitors in parallel have a capacity of , and , respectively. What is the total capacitance?

Possible Answers:

Correct answer:

Explanation:

The formula for capacitors in parallel is:

Plug in our given values:

Example Question #2 : Using Capacitor Equations

Three capacitors in series have a capacity of , and , respectively. What is the total capacitance?

Possible Answers:

Correct answer:

Explanation:

The formula for capacitors in series is:

Plug in our given values:

 

Example Question #3 : Using Capacitor Equations

Three capacitors of equal capacitance are in a series circuit. If the total capacitance is , what is the capacitance of each individual capacitor?

Possible Answers:

Correct answer:

Explanation:

The formula for capacitors in a series is:

Since we have three equal capacitors, we can say:

Using the value for total capacitance, we can find the value for the individual capacitance.

Example Question #4 : Using Capacitor Equations

Three capacitors of equal capacitance are in a parallel circuit. If the total capacitance is , what is the capacitance of each individual capacitor?

Possible Answers:

Correct answer:

Explanation:

The formula for capacitors in parallel is:

Since we have three equal capacitors, we can say:

Use the value for total capacitance to find the individual capacitance value.

 

Example Question #1 : Magnetism And Electromagnetism

A current of  runs through a straight wire. If the resulting magnetic field has a radius of , how strong is the magnetic field?

Possible Answers:

Correct answer:

Explanation:

Ampere's law states: 

.

In other words, the magnetic field (), is equal to a constant () times the current () divided by the circumference of the magnetic field it is creating.

We are given the current, the constant, and the radius. Using these values, we can solve for the magnetic field strength.

Notice that the  cancels out.

Example Question #2 : Magnetism And Electromagnetism

A current runs through a wire such that it generates a magnetic field. The magnetic field is in the clockwise direction in the plane of your computer screen. What is the direction of the current?

Possible Answers:

Into the screen

Out of the screen

Counter-clockwise

More information is needed to solve

Clockwise

Correct answer:

Into the screen

Explanation:

To solve this problem use the right hand rule. Take your right hand and make a fist. Now stick your thumb straight up. This will show you the relationship between current and magnetic field: if the magnetic field is your fingers, the current is your thumb.

In this problem, the only way you can get your fingers to be going clockwise in a plane is if your thumb is pointed directly at that plane. Point your thumb directly at the screen. Your fingers will naturally curl in the clockwise direction. The current must be going into the screen.

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