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Subelement B
Electrical Math
Section 15
RC Time Constants-2
What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors all in parallel?
  • 22 seconds.
  • 44 seconds.
  • 440 seconds.
  • Correct Answer
    220 seconds.

What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors all in parallel?

220 seconds.

From imfv!fn20xe93iyimqwrsdcjpnu=.

The Time Constant (T) is calculated as follows:
      \[T = R C\]

Since the components are all in parallel, calculate the total resistance and capacitance separately and then multiply R and C to get the time constant.

Total Resistance: \[(1M ∗ 1M) ÷ (1M + 1M) = 500 k\] Total Capacitance: \[(220 uF + 220 uF) = 440 uF \] Time Constant: \[(500 k) ∗ (440 uF) = 220 s\]

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What is the time constant of a circuit having two 100-microfarad capacitors and two 470-kilohm resistors all in series?
  • 470 seconds.
  • Correct Answer
    47 seconds.
  • 4.7 seconds.
  • 0.47 seconds.

What is the time constant of a circuit having two 100-microfarad capacitors and two 470-kilo ohm resistors all in series?

47 seconds.

From doughboy_260.:

\begin{align} Time Constant = C Total \times R Total\\ C Total = 1 \div ((1 \div .0001) + (1 \div .0001))\\ =.00005\\ \\ R Total = 470000 + 470000\\ = 940000\\ \\ T = .00005 \times 940000\\ =47 \end{align}

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What is the time constant of a circuit having a 100-microfarad capacitor and a 470-kilohm resistor in series?
  • 4700 seconds.
  • 470 seconds.
  • Correct Answer
    47 seconds.
  • 0.47 seconds.

What is the time constant of a circuit having a 100-microfarad capacitor and a 470-kilohm resistor in series?

47 seconds.

From badwolf.j:

Convert microfarad and kilohm to their base units and multiply.

100 microfarad = 0.0001 farad

470 kilo ohm = 470000 ohms

\[0.000100 farad ∗ 470,000 ohms = 47 seconds\]

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What is the time constant of a circuit having a 220-microfarad capacitor and a 1-megohm resistor in parallel?
  • Correct Answer
    220 seconds.
  • 22 seconds.
  • 2.2 seconds.
  • 0.22 seconds.

What is the time constant of a circuit having a 220-microfarad capacitor and a 1-megohm resistor in parallel?

220 seconds.

From xrt70r:

RC Time Constant= R ∗ C

(1 x 106) ∗ (220 x 10-6) = 220 seconds

Last edited by markadlerdallas. Register to edit

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What is the time constant of a circuit having two 100-microfarad capacitors and two 470-kilohm resistors all in parallel?
  • 470 seconds.
  • Correct Answer
    47 seconds.
  • 4.7 seconds.
  • 0.47 seconds.

What is the time constant of a circuit having two 100-microfarad capacitors and two 470-kilohm resistors all in parallel?

47 seconds

From wp2ahg:

Convert from microfarads and kilo ohms to farads and ohms before doing the calculation:

470,000 ohms ∗ 0.000100 farad = 47 seconds

Last edited by markadlerdallas. Register to edit

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What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors all in series?
  • Correct Answer
    220 seconds.
  • 55 seconds.
  • 110 seconds.
  • 440 seconds.

What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors all in series?

220 seconds.

From doughboy_260:

The equivalent resistance of two \(1 MΩ\) resistors in series is \(2 MΩ\).

The equivalent capacitance of two \(220 μF\) capacitors in series is \(110 μF\).

The time constant is \[R \times C = ({110 \times 10^{-6}}) \times (2 \times 10^6) = 220 s\].

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