Transient Response of RC circuits
Objective
Plot the voltage across a capacitor, when it is charged by applying a voltage step through a resistor. Extract the value of RC from the graph by curve fitting.h.
Procedure
- Make connections as shown in the figure
- Click on 0->5V STEP and 5->0V step Buttons to plot the graphs
- Adjust the horizontal scale, if required, and repeat.
- Calculate RC time constant.

Discussion
Applying a 0 to 5V step makes the voltage across the capacitor to rise
exponentially as shown in the figure. By fitting the discharge curve
with , we can extract the RC time
constant and find the values of capacitance from it.
The voltage across a capacitor is exponential only when it is charged
trough a linear element, a resistor for example. When charged from a
constant current source, the voltage shows linear increase, because
, and voltage increases linearly with time as
.
For detailed description of the theory of RC ircuits visit KhanAcademy