Charging a Capacitor

Part of the Electricity and Magnetism section of Coddy's Physics journey. Lesson 35 of 51.

Charging through a resistor, the charge rises toward $Q = C\varepsilon$ :

$q = Q\left(1 - e^{-t/RC}\right)$

A charging circuit

The time constant:

$\tau = RC$

after one τ, 63% of Q; after five τ, practically full.

The charging curve

Challenge

A $12\ \mathrm{V}$ battery charges an empty $100\ \mathrm{\mu F}$ capacitor through a $10\ \mathrm{k\Omega }$ resistor. How much charge $q$ does the capacitor hold $1\ \mathrm{s}$ after the switch closes?

Try it yourself

Solve for $q$

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Electricity and Magnetism

1Electric Charge and Force

Electric Charge Coulomb's Law Several Charges Recap - Charges in a Line

4Charged Conductors

The Charged Sphere Connecting Spheres Recap - Beam Between Plates

7Real Batteries

Internal Resistance The Variable Resistor Ammeters and Voltmeters Recap - Flashlight

10Magnetic Fields

Magnets and Magnetic Fields Field of a Wire Loops and Solenoids Recap - Electromagnet

2The Electric Field

The Electric Field Field of Several Charges The Uniform Field A Charge in a Uniform Field Recap - Stopping a Proton

5Capacitors

The Capacitor Combining Capacitors Changing a Capacitor Recap - Camera Flash

8Kirchhoff's Laws

The Junction Rule The Loop Rule Solving Two Loops Recap - Charging a Battery

11Magnetic Forces

Force on a Moving Charge Circles in a Field Force on a Wire Two Parallel Wires Recap - Current Balance

3Energy and Potential

Electric Potential Energy Electric Potential Field and Potential Recap - Accelerating Ions

6Current and Resistance

Current and Voltage Resistance and Ohm's Law Series and Parallel Electric Power Recap - Fairy Lights

9Capacitors in Circuits

A Capacitor in a CircuitCharging a CapacitorDischarging a Capacitor Recap - Defibrillator

12Induction

A Rod Moving in a Field Magnetic Flux Faraday's Law Lenz's Law Recap - Generator