Electrical and Electronic Principles – I (ENGD1103)

Title of the Assignment: RC Circuit; Charging and Discharging of Capacitors and Equivalent Capacitance

ASSESSMENT:

Please complete this coursework by completing this lab sheet (word processed – try to limit your comments & answers to the allocated textboxes, expanding only if necessary).

OBJECTIVES:

1. To investigate the characteristics of charging and discharging of a capacitor through a resistor.
2. To develop an understanding of capacitors in series and parallel and the relation between charge, voltage and capacitance.

In this lab a signal generator is employed to perform the switching, and an oscilloscope to display the voltage across the capacitor.

1. The Time Constant, τ=RC:

Consider the circuit below using a 820Ω resistor and a 1μF capacitor.

1. For the given input voltage signal, draw the input and output waveforms expected using a graph sheet if possible.

2. Draw atleast 1 cycle of charging and 1 cycle of discharge of the capacitor.

3. Label the time constants for both charging and discharging periods.

1. Time Constants

For an input voltage of 10Vp-p square waveform, complete the following tables. The theoretical value of R = 820Ω and C = 1μF.

1. DISCUSSIONS

• Compare the above two tables.
• Write the expression for capacitor voltage during the charging phase and
• Explain the effect of different values of R and C