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Chapter 7 - Electric and Magnetic Fields - Capacitor Discharge
11問 • 2年前
  • Oluwole Akande
  • 通報

    問題一覧

  • 1

    How do you discharge a capacitor

    Connect it to a circuit with just a resistor (no power supply)

  • 2

    Why does a Capacitor discharge

    When a capacitor is connected to a resistor, the resistor provides a path for charge to flow between plates, This causes charge on a fully charged capacitor to flow from the positive plate, around the circuit to the negative plate , As charge flows, the potential difference across the plates decreases and the electric field strength decreases, This decreases the rate of charge flow away from the circuit until it is fully discharged, once the p.d. across both plates is zero

  • 3

    Charge Stored on Capacitor, Q (Coulombs, C) =

    Initial Charge Stored, Q⁰ (Coulombs, C) × e^(-Time, t / Resistance × Capacitance)

  • 4

    Time for the Charge to Halve, t (s) =

    ln|2| × Resistance, R (Ohms) × Capacitance, C (Farads, F)

  • 5

    What is the Time Constant and the Implications of the Time Constant

    Time Constant is the product of resistance and capacitance, This means that with each time constant, the charge will decrease by a constant fraction

  • 6

    Potential Difference of a Capacitor, V (Volts, V) =

    Initial Potential Difference, V0 (Volts, V) × e^(-Time, t / Resistance, R × Capacitance, C)

  • 7

    Current Through a Capacitor, I (Amps, A) =

    Initial Current, I0 (Amps, A) × e^(-Time, t / Resistance, R × Capacitance, C)

  • 8

    How are the Equations for current and voltage in a charging/discharging capacitor derived

    Voltage equation is found by substituting the equation for capacitance (Q = CV) into the equation for charge of a (dis)charging capacitor, Current equation is found by substituting the Ohm's law equation (V = IR) into the equation for Voltage of a (dis)charging capacitor

  • 9

    How else can the Initial Current be Calculated

    Initial Current, I0 = Initial Potential Difference, V0 / Resistance, R

  • 10

    What is the Time Constant

    The product of resistance and capacitance, Time to discharge a capacitor to 1/e (≈ 37%) of its initial value of charge, current, or voltage, Time to charge a capacitor to (1 - 1/e) (≈63%) of its maximum value of charge or voltage

  • 11

    How can the time constant be found graphically

    From -1/Gradient, where the gradient is taken from a graph of lnQ over time

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    問題一覧

  • 1

    How do you discharge a capacitor

    Connect it to a circuit with just a resistor (no power supply)

  • 2

    Why does a Capacitor discharge

    When a capacitor is connected to a resistor, the resistor provides a path for charge to flow between plates, This causes charge on a fully charged capacitor to flow from the positive plate, around the circuit to the negative plate , As charge flows, the potential difference across the plates decreases and the electric field strength decreases, This decreases the rate of charge flow away from the circuit until it is fully discharged, once the p.d. across both plates is zero

  • 3

    Charge Stored on Capacitor, Q (Coulombs, C) =

    Initial Charge Stored, Q⁰ (Coulombs, C) × e^(-Time, t / Resistance × Capacitance)

  • 4

    Time for the Charge to Halve, t (s) =

    ln|2| × Resistance, R (Ohms) × Capacitance, C (Farads, F)

  • 5

    What is the Time Constant and the Implications of the Time Constant

    Time Constant is the product of resistance and capacitance, This means that with each time constant, the charge will decrease by a constant fraction

  • 6

    Potential Difference of a Capacitor, V (Volts, V) =

    Initial Potential Difference, V0 (Volts, V) × e^(-Time, t / Resistance, R × Capacitance, C)

  • 7

    Current Through a Capacitor, I (Amps, A) =

    Initial Current, I0 (Amps, A) × e^(-Time, t / Resistance, R × Capacitance, C)

  • 8

    How are the Equations for current and voltage in a charging/discharging capacitor derived

    Voltage equation is found by substituting the equation for capacitance (Q = CV) into the equation for charge of a (dis)charging capacitor, Current equation is found by substituting the Ohm's law equation (V = IR) into the equation for Voltage of a (dis)charging capacitor

  • 9

    How else can the Initial Current be Calculated

    Initial Current, I0 = Initial Potential Difference, V0 / Resistance, R

  • 10

    What is the Time Constant

    The product of resistance and capacitance, Time to discharge a capacitor to 1/e (≈ 37%) of its initial value of charge, current, or voltage, Time to charge a capacitor to (1 - 1/e) (≈63%) of its maximum value of charge or voltage

  • 11

    How can the time constant be found graphically

    From -1/Gradient, where the gradient is taken from a graph of lnQ over time