The aim of the experiment is to understand the properties of the passive elements and the resonance.


1. Unknown Box

2. Passive Elements: Resistors, Inductors and Capacitors

3. A.C. Power supply

4. Connecting Wires

5. Multimeter

Introductory Theory

Passive elements

Passive elements are elements that can either absorb energy or store energy.

There are 3 types of passive elements, which are shown below:

Resistor: A resistor is a two-terminal electrical or electronic component that resists an electric current by producing a voltage drop between its terminals in accordance with Ohm's law.

Inductor: An inductor is a passive electrical device employed in electrical circuits for its property of inductance. It stores energy in magnetic form.

Capacitor: A capacitor is a device that stores energy in the electric field created between a pair of conductors on which equal but opposite electric charges have been placed.


It is a box which contains an unknown passive element other than a resistor. Both of them are connected in series.


A circuit is said to be in resonance when its impedance is equal to its resistance. There are two types of resonant circuit: Series and Parallel.

2 types of resonant circuits are shown as the following:

Series Resonant Circuit: Passive elements are connected in series.

Parallel Resonant Circuit: Passive elements are connected in parallel.


Experiment 1: Unknown Component


The blackcontains an unknown passive element other than a resistor and it is connected to a resistor in series. The objective is to find the unknown component in the black box.


1) The unknown box is connected in series with a resistor, R in the circuit.

2) An AC power supply is connected to the circuit.

3) The potential different is set to be 1V throughout the experiment.

4) A multimeter is connected across the unknown box to measure its...
tracking img