Lab no. 2
Theory
Kirchhoff’s Laws
1st Kirchhoff’s Law– law relates the current flow in the circuit
branches:
For the circuit node algebraic sum of the intensities of currents entering
(+) and leaving (-) is equal to zero.
Build the circuit as shown, check that the current from the source
measured by an ammeter XMM4 is equal to the sum of currents flowing
through the resistors R1-R3
Change the resistance values R1-R3
Kirchhoff's second law– also called voltage law, applies to the balance
of voltages in the closed direct current circuit.
In the closed circuit voltage drop on the sum of resistances is the sum of
electromotive forces present in the circuit.
Build the circuit as shown, check that the voltage source is equal to the
sum of voltage drops on the resistances in all meshes of the circuit.
Repeat the measurements for other resistances
Determine the resistance of alternative systems from the drawing. Make
the simulation (you can use a multimeter as an ohmmeter).
Compare the results of measurements with theoretical calculations
Calculation of electric circuits based on Kirchhoff's laws
Determine the voltage source V1 and the resistance R3, so that the
currents I1 = I2 = 500mA
Determine the resistance R6 and R8, so that no current would flow
through the resistor R8 (I1 = 0)
Current-voltage characteristics of a typical diode[Source: Wikipedia]
Build the circuit as shown.
This is called. wave rectifier. The AC voltage source is used. Set the
voltage to 10V, AC Analysis Magnitude to 0V.
full-wave rectifier
Add filter capacitor
Change the value of the capacitor so the voltage at the load R was
almost a straight line, then decrease the resistance R
Practice
All circuits are placed on ”breadboard” from NI ELVIS.
Holes from each row are
connected together
Bulk line
Supply line
Function Generator (bulk is already connected)
Oscilloscope inputs
Inputs for Multimeter
Regulated Power Supply
DC Power Supply
1st Kirchoff’s Law
Build the circuit and connect nodes.
Measure current between J5 and J6.
Measure current flowing into the node.
Measure current flowing through R1
Measure accordingly for R2 and R3. Check if the currents’ sum is
correct.
Half Wave Rectifier
Build the circuit as presented beneath.
Voltage of the generator: sinusoidal with 10 Vpp amplitude
Measure input and output signals.
Rectifying Diode
Complete the system with capacitor filter. Note the polarity of the
capacitor is important. The negative pole is marked on the
capacitor’s cover.
Observe how the capacitor influences the output signal.
Change the resistance from 5kOhm to 470 Ohm.
Observe signal’s change.
Modify the circuit by changing polarization of the diode. Observe
the change.