capacitors

    Cards (30)

    • What is the symbol for a capacitor?
      Two parallel lines
    • What is the primary function of a capacitor?
      To store electrical charge
    • How is the charge stored on a capacitor related to potential difference?
      Charge is proportional to potential difference
    • What is the formula for capacitance?
      c=c =qv \frac{q}{v}
    • What does capacitance measure?
      Charge stored per unit potential difference
    • What is the unit of capacitance?
      Farad
    • How is one farad defined?
      One coulomb stored per one volt
    • Describe the flow of electrons when a capacitor charges.
      Electrons flow from negative cell to negative plate
    • What happens to the charges on the plates of a capacitor during charging?
      Plates acquire equal and opposite charges
    • How can a charged capacitor be used in a circuit?
      As a power source for a light bulb
    • What is the rule for adding capacitors in parallel?
      • Total capacitance is the sum of individual capacitances:
      • Ctotal=C_{total} =C1+ C_1 +C2 C_2
    • What is the total capacitance of two 300 microfarad capacitors in parallel?
      600 microfarads
    • What is the rule for adding capacitors in series?
      • Total capacitance is given by:
      • 1Ctotal=\frac{1}{C_{total}} =1C1+ \frac{1}{C_1} +1C2 \frac{1}{C_2}
    • What is the total capacitance of two 300 microfarad capacitors in series?
      150 microfarads
    • Why is the rule for adding capacitors in series different from that for resistors?
      Capacitors store charge differently than resistors
    • How is total charge calculated in a parallel circuit?
      Total charge is the sum of individual charges
    • What does Kirchhoff's second law state about potential difference in a series circuit?
      Sum of emf equals sum of potential differences
    • What is the relationship between voltage and charge in a parallel circuit?
      Voltage is the same across all branches
    • How does voltage change during the discharging of a capacitor?
      Voltage decreases exponentially over time
    • What is the equation for voltage across a discharging capacitor?
      v=v =v0etcr v_0 e^{-\frac{t}{c r}}
    • What is the initial voltage of a 500 microfarad capacitor charged to 6 volts?
      6 volts
    • How do you calculate the voltage across a capacitor after 150 seconds of discharging?
      Use v=v =v0etcr v_0 e^{-\frac{t}{c r}}
    • What is the time constant for a capacitor?
      τ=\tau =cr c \cdot r
    • What does the time constant indicate in a capacitor circuit?
      Time for voltage to drop to 37%
    • How can the time constant be derived from the units of capacitance and resistance?
      It has units of time (seconds)
    • What happens to voltage at the time constant?
      Voltage drops to 37% of initial value
    • How can you determine capacitance from a discharge graph?
      Use time constant and resistance relationship
    • What is the equation for voltage across a charging capacitor?
      vc=v_c =v0(1etcr) v_0 (1 - e^{-\frac{t}{c r}})
    • How does current behave in a charging capacitor circuit?
      Current decreases as capacitor charges
    • What happens to the current when the capacitor is fully charged?
      Current drops to zero
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