THEORY
Current
Current is the movement of electrons from negatively charged atoms to positively
charged atoms. It is the sum of the charges of the moving electrons past a certain point
in the circuit. The symbol of current is expressed as (I). Current is measured in the unit
called ampere (A) or the charge per second on a single point. The name ampere is
named after André Marie Ampère. Current can be determined using ohm’s law (I = V/R)
Voltage
Voltage is the force that moves the electrons in the circuit to create an electrical current.
It is sometimes referred as the potential difference. The potential is the ability of the
source to perform electrical work. The unit for measuring voltage is volt (V) named after
Count Alessandro Volta who invented the first cell to produce electricity. Voltage can be
determined using ohm’s law (V=IR)
Resistors
Resistance is the opposition to the flow of electrons (current in a circuit). Current
decreases as the resistance on a certain point of a circuit increases. Every material has
their own resistance that varies depending on the composition, size, shape and
temperature of the material. Resistance is measured in units called ohms named after
German physicist George Simon Ohm and it is abbreviated as Ω
Resistor is an electronic component whose function is to limit the flow of current in an
electric circuit or to provide a voltage drop. Resistors are essential in order to ensure
that current flows at the appropriate level in circuits. They varied in values, shapes and
sizes. The value of resistance can be determined by the color-coded bands.
Digital Multimeter
A multimeter is an electronic device used to test various electrical measurements such
as AC and DC voltage, current, and resistance. It combines the function of a voltmeter,
ammeter, and ohmmeter. Multimeter also includes other functions, such as diode test,
continuity test, transistor test, and frequency test.
3 Main Parts of Multimeter:
Display - The display shows the values of electrical parameters being measured. A few
multimeters have illuminated displays for better viewing in low light situations.
Selection Knob - The selection knob allows the user to set the multimeter to read
different things such as milliamps (mA) of current, voltage (V) and resistance (Ω).
Ports - Two probes are plugged into two of the ports on the front of the unit. The black
lead is always plugged into the common terminal. The red lead is plugged into the 10 A
jack when measuring currents greater than 300 mA, the 300 mA jack when measuring
currents less than 300 mA, and the remaining jack (V-ohms-diode) for all other
measurements.
To measure the voltage and resistance of a component or circuit, simply put the red
probe on the positive end of the component and the black probe on the other end. On
the other hand, when measuring amperes, disconnect the part of the circuit that to be
measured. Connect the red probe on the opening of the circuit and the black on the
other opening. The digital multimeter will complete the circuit and measure the current
passing through that part of the circuit.
Breadboard
A board on which any circuit can be set up to provide inter connections between
electronics components and devices. The components on the breadboard can be
connected or disconnected easily without soldering and any other special instruments. It
has both horizontal and vertical set of holes. Every five of the horizontal holes are
connected in every column whereas the vertical holes are connected with their rows.
Oscilloscope
Oscilloscope is an electronic device which is capable of giving a visual indication of a
signal waveform. With an oscilloscope the waveform of the signal can be determine.
Oscilloscope can also be used for measuring voltage, frequency and phase shift. The
screen of the oscilloscope has a grid on it called a gradecule. The gradecule is used to
read information from the screen of the oscilloscope. The display is broken up into socalled horizontal divisions (horizontal div) and vertical divisions (vertical div). The trace
on an oscilloscope screen is a graph of voltage against time. The shape of the wave in
the graph is determined by the nature of the input signal. The user can then examine
this graph to discover the amplitude, frequency, and overall form of the signal, which
may vary depending on the signal being studied in the experiment.
Function Generator
Function generator is electronic test equipment used to generate different types of
waveforms over a wide range of frequencies. Function generators are capable of
producing a variety of repetitive waveforms such as sine wave, square wave, triangle
wave, etc. It contains buttons for the selection of frequency range and signal wave type
generated by AC signal. We can select any waveform and frequency range by pressing
the buttons on the Function Generator.
Observation
In the experiment, equipment and components such as resistors, breadboard,
digital multimeter, oscilloscope and function generator were used.