🔖 Topics

  • Series RC circuits

🎯 Objectives

  • Calculate the charge on a capacitor as a function of time in a simple charging RC circuit
  • Calculate the charge on a capacitor as a function of time in a simple discharging RC circuit
  • Calculate the current as a function of time in a simple charging RC circuit
  • Calculate the current as a function of time in a simple discharging RC circuit

📋 Sequence

  • Overview of RC circuits
  • Time constants
  • Charging circuits
  • Discharging circuits

🖥️ Animations, Simulations, Activities

📝 Practice Problems

  1. A capacitor of \( 0.10 \: \mu F\) is charged to 90 V and then connected to a \( 30 \: k \Omega \) resistor. What will the voltage across the resistor be after 8.4 ms?
  2. A capacitor of \( 0.050 \: \mu F \) is initially uncharged and connected in series to a 12 V battery and a \( 40 \: k \Omega \) resistor. What is the current in the circuit at time t = 0 seconds? What is the current in the circuit at time t = 1 second?
  3. In a charging RC circuit, how many time constants have elapsed when the capacitor has 99% of its final charge?

✅ Partial Solutions

  1. 5.5 V
  2. 0.30 mA; 0.18 mA
  3. 4.6

📘 Connected Resources

  • Duffy, Andrew. “RC Circuit.” RC Circuit, https://physics.bu.edu/~duffy/HTML5/RC_circuit.html, January 2018.
  • Giambattista, Alan, et al. College Physics With an Integrated Approach to Forces and Kinematics. 5th ed., McGraw-Hill Education, 2020.