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Questions and Answers
In a scenario where a capacitor is being charged, what describes the movement of electrons?
In a scenario where a capacitor is being charged, what describes the movement of electrons?
- Electrons move from the plate with high electric potential to the plate with low electric potential. (correct)
- Electrons move from the plate with low electric potential to the plate with high electric potential.
- Electrons accumulate on both plates equally, creating a balanced charge.
- Electrons move randomly between both plates until equilibrium is achieved.
A capacitor with a capacitance of 4 farads is charged to a potential difference of 12 volts. Determine the magnitude of the charge?
A capacitor with a capacitance of 4 farads is charged to a potential difference of 12 volts. Determine the magnitude of the charge?
- 48 Coulombs (correct)
- 3 Coulombs
- 16 Coulombs
- 0.33 Coulombs
What is the primary distinction between polarized and non-polarized capacitors?
What is the primary distinction between polarized and non-polarized capacitors?
- Polarized capacitors are typically used in high-frequency applications.
- Non-polarized capacitors are generally larger in size compared to polarized capacitors.
- Non-polarized capacitors always have higher capacitance values.
- Polarized capacitors have a specific positive and negative orientation, while non-polarized capacitors do not. (correct)
A capacitor has a capacitance of 5 microfarads without a dielectric. When a dielectric material is inserted, the capacitance increases to 25 microfarads. What is the dielectric constant of the material?
A capacitor has a capacitance of 5 microfarads without a dielectric. When a dielectric material is inserted, the capacitance increases to 25 microfarads. What is the dielectric constant of the material?
A capacitor with a capacitance of 2 microfarads is charged to a potential difference of 10 volts. How much energy is stored in the capacitor?
A capacitor with a capacitance of 2 microfarads is charged to a potential difference of 10 volts. How much energy is stored in the capacitor?
Which of the following adjustments to a capacitor's physical characteristics will increase its capacitance?
Which of the following adjustments to a capacitor's physical characteristics will increase its capacitance?
A 10 microfarad capacitor is charged to 50V. After being disconnected from the voltage source, a dielectric with constant k = 2 is inserted without discharge. What is the new voltage across the capacitor?
A 10 microfarad capacitor is charged to 50V. After being disconnected from the voltage source, a dielectric with constant k = 2 is inserted without discharge. What is the new voltage across the capacitor?
A parallel-plate capacitor has a capacitance of 6 F with air as the dielectric. What will the capacitance be if a dielectric material with a constant of 3 is inserted, assuming all other factors remain unchanged?
A parallel-plate capacitor has a capacitance of 6 F with air as the dielectric. What will the capacitance be if a dielectric material with a constant of 3 is inserted, assuming all other factors remain unchanged?
The energy density in a capacitor is 5 J/m when the electric field magnitude is $1 \times 10^6$ V/m. Given that $u = \frac{1}{2} \epsilon_0 E^2$, what is the approximate permittivity of free space ($\epsilon_0$)?
The energy density in a capacitor is 5 J/m when the electric field magnitude is $1 \times 10^6$ V/m. Given that $u = \frac{1}{2} \epsilon_0 E^2$, what is the approximate permittivity of free space ($\epsilon_0$)?
If the plate separation of a capacitor is doubled while the voltage remains constant, how does the stored charge change?
If the plate separation of a capacitor is doubled while the voltage remains constant, how does the stored charge change?
Flashcards
Capacitors
Capacitors
Passive components that store electric charge and electric potential energy in electronic circuits.
Capacitor Charging
Capacitor Charging
The process where electrons accumulate on a capacitor's plates when connected to a power supply.
Capacitance (C)
Capacitance (C)
The measure of a capacitor's ability to store charge per volt, measured in Farads (F).
Polarized Capacitors
Polarized Capacitors
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Dielectric Constant (k)
Dielectric Constant (k)
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ε₀
ε₀
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Energy Stored (U)
Energy Stored (U)
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Energy Density (u)
Energy Density (u)
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Plate Area (A)
Plate Area (A)
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Plate Separation (d)
Plate Separation (d)
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Study Notes
Capacitors in Electronic Circuits
- Capacitors are essential passive components in electronic circuits, capable of storing electric charge and electric potential energy.
- Technological advancements rely on electronic circuits, where capacitors play a vital role.
- A capacitor stores electric potential energy and electric charge.
- Capacitors have two conducting plates separated by a dielectric material.
Capacitor Functionality
- Capacitors undergo a charging process where electrons flow from one plate to another when connected to a power supply.
- Initially, capacitors are uncharged and become charged when connected to a power supply.
- Electrons move from a plate with high potential to a plate with low potential during charging.
- The difference in charge between the plates allows a capacitor to act as a temporary battery.
- Capacitors enable electronic devices to function even with alternating current supplies.
Capacitance Measurement
- The amount of energy a capacitor can hold is measured by capacitance (C), defined as C = Q/V.
- C = Capacitance, measured in Farads (F), named after Michael Faraday.
- Q = Magnitude of charge, measured in Coulombs.
- V = Magnitude of electric potential (voltage).
- Capacitance measures the amount of charge a capacitor can hold per volt and is the ratio of charge to voltage.
- The formula can be rearranged to Q = CV to find the magnitude of charge.
Types of Capacitors
- Common capacitor types:
- Electrolytic
- Ceramic
- Mica
- Paper
- Film
- Non-polarized
- Polarized capacitors, like electrolytics, have a specific positive and negative orientation.
- Different capacitor types vary based on construction materials and dielectric properties.
- Construction impacts how much capacitance a capacitor can store.
Capacitor Construction and Capacitance
- Capacitance is determined by: C = kε₀(A/d)
- C = Capacitance
- k = Dielectric constant
- ε₀ = Permittivity of free space, approximately 8.85 x 10⁻¹² F/m
- A = Plate area
- d = Distance between plates
- Dielectric constant (k) depends on the material used and can be found online, varying for different materials.
- Capacitance with a dielectric (Ck) is calculated as Ck = kC₀, where C₀ is capacitance without a dielectric.
- Voltage with a dielectric effect (Vk) is calculated as Vk = V₀/k, where V₀ is voltage without a dielectric.
Energy and Capacitance Relationship
- Capacitors store energy, and energy (U) is calculated as U = ½ QV.
- Substituting Q = CV, energy can also be expressed as U = ½ CV².
- Using V = Q/C, energy can also be expressed as U = Q²/2C.
- Energy is measured in Joules.
- Energy density (u) is the amount of electrical potential energy stored in the system: u = ½ ε₀E², where E is the electric field magnitude.
- Energy density is measured in Joules per cubic meter (J/m³).
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