Charging/Discharging

Voltage of Battery

Resistance of Light Bulb

Inductance of Inductor




I [A] t [s] 2 4 6 8 10 1 2 3 –1 –2 –3 4 –4 V   R [V] t [s] 2 4 6 8 10 4 8 12 –4 –8 –12 V L [V] t [s] 2 4 6 8 10 4 8 12 –4 –8 –12 < dI/dt [A/s] t [s] 2 4 6 8 10 1.5 3.0 4.5 –1.5 –3.0 –4.5 6.0 –6.0 100% ≈63% 5.3s The time constant is the time for the curve to change by approximately 63%. When the horizontal green and horizontal black lines are properly placed, the horizontal distance between the two vertical blue lines is the time constant. Drag to the asymptotic value Drag to the initial value Close Time Constant Tool Close Time Constant Tool Help
Enter expressions for the initial and final values and the time constant for the quantity being graphed in terms of:

  • A numeric value
Initial Value =
A/s

Asymptotic Value =
A/s

Time Constant =
s

  • R = resistance of the light bulb
  • C = capacitance of the capacitor
  • Vb = voltage across the battery
Initial Value =
A/s

Asymptotic Value =
A/s

Time Constant =
s

Enter expressions for the quantity being graphed in terms of:

  • t = time
  • Numeric values
  • Functions such as sin( ), cos( ), exp( ) or ln( )
dI(t) =

  • t = time
  • R = resistance of the light bulb
  • C = capacitance of the capacitor
  • Vb = voltage across the battery
  • Functions such as sin( ), cos( ), exp( ) or ln( )
dI(t) =

The actual curve is red. The curve corresponding to your numeric function is green. The curve corresponding to your symbolic function is blue.