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Example Questions
Example Question #41 : Electricity And Magnetism
Two resistors in series have and resistance, respectively. What is the total resistance?
For resistors in a series, total resistance is equal to the sum of each individual resistance.
We can use the individual resistances from the question to solve for the total resistance.
Example Question #8 : Calculating Total Resistance
What is the total resistance of a series circuit with resistors of , , and ?
For a series circuit, the formula for total resistance is:
We are given the values of each resistance, allowing us to sum them to find the total resistance in the circuit.
Example Question #41 : Electricity And Magnetism
What is the total resistance of a parallel circuit with resistors of , , and ?
The formula for resistance in parallel is:
We are given the values for each individual resistor, allowing us to solve for the total resistance.
Example Question #42 : Electricity And Magnetism
Calculate the resistance of a copper wire with cross-sectional area of and length of .
The resistance of a wire is given by the following equation:
We are given the resistivity (), cross-sectional area, and length. Using these values, we can solve for the resistance.
First, convert the cross-sectional area to square-meters.
Use the resistance equation to solve.
Example Question #11 : Calculating Total Resistance
What is the total resistance of a , , and series circuit?
The formula for resistors in series is .
Plug in our given values.
Example Question #41 : Electricity And Magnetism
There are three resistors in parallel in a circuit with resistances of , , and .
What is the equivalent resistance?
The equation for resistors in parallel is:
We are given the values of the resistors. Using this formula, we can solve for the equivalent resistance.
Plug in the given values and solve.
Example Question #42 : Electricity And Magnetism
Which of these is the correct SI unit for capacitance?
Newtons
Volts
Farad-Joules
Farads
Ohms
Farads
The correct unit for capacitance is the Farad, named after the English physicist Michael Faraday.
Newtons are used to measure force. Ohms measure resistance and volts measure electrical energy or potential. Joules are a unit of energy, but Farad-Joules are not a recognizable unit.
Example Question #43 : Electric Circuits
By using a dielectric, it is possible to store more energy in a capacitor. Why is this?
The dielectric changes the distance between the two plates of the capacitor
The dielectric provides a direct energy source to the capacitor
The dielectric can store excess energy
The dielectric replaces air, which breaks down when the electric fields get strong enough
The dielectric replaces air, which breaks down when the electric fields get strong enough
Dielectrics are insulating materials that can be polarized, and can be used to increase the separability of the two plates of a capacitor. When a dielectric is absent, air is present between the capacitor plates. At high voltages, when the electric field between the plates is incredibly strong, air begins to break down and becomes unable to prevent the flow of electricity between the capacitor plates. When this occurs, the capacitor cannot store energy, nor can it properly function. The presence of a dielectric eliminates this problem, allowing the capacitor to store much more energy.
Example Question #45 : Electricity And Magnetism
Three capacitors are in series. They have capacitances of , , and , respectively. What is their total capacitance?
For capacitors in series the formula for total capacitance is:
Note that this formula is similar to the formula for total resistance in parallel. Using the values for each individual capacitor, we can solve for the total capacitance.
Example Question #43 : Electricity And Magnetism
Three capacitors are in parallel. They have capacitance values of , , and . What is their total capacitance?
For capacitors in parallel the formula for total capacitance is:
Note that this formula is similar to the formula for total resistance in series. Using the values for each individual capacitor, we can solve for the total capacitance.
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