Kirchhoff’s Laws
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Naam
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Part A
Kirchhoff’s Current Law
To investigate and verify Kirchhoff’s Current Law.
Kirchhoff’s current law states that the current entering a junction
is the same as the current exiting the junction.
Junction
1. Build your own circuit using wires and resistors provided in
OhmZone. You can make either a parallel circuit or a combination
series-parallel circuit. Your circuit should have several places
where at least 3 wires meet. These are called junctions or nodes.
Choose one of these junctions to analyze.
a. Use the VISUALIZE feature of OhmZone to determine
whether current is entering or exiting the junction and
indicate in the table on the following page.
Gustav Robert
Kirchhoff
(1824-1887)
b. Place the ammeter on each wire at this intersection to
measure the current entering or exiting the junction and
record the values.
c. Calculate the sum of the currents entering the junction and
the sum of the currents exiting the junction. Compare the
two sums.
d. Repeat these steps with different junctions in your circuit.
Use the table on the following page to record your measurements and
calculated values.
Kirchhoff’s Laws
1
By John Roberts
B
C
D
Total Current (A)
Entering Junction
Total Current (A)
Exiting Junction
Same or
Different
Exiting or
Entering
Junction
A
Current (A)
Wire 1 =
Wire 2 =
Wire 3 =
Wire 4 =
Wire 1 =
Wire 2 =
Wire 3 =
Wire 4 =
Wire 1 =
Wire 2 =
Wire 3 =
Wire 4 =
Wire 1 =
Wire 2 =
Wire 3 =
Wire 4 =
What do you notice about the sums of the currents entering and
exiting the junctions?
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Part B Kirchhoff’s Voltage Law
To investigate voltages in a series circuit and in a parallel circuit.
1. Build a series circuit.
a. Using the voltmeter provided, measure the voltage across
the battery and the potential difference (voltage) across
each individual resistor.
b. Build four more series circuits and repeat the
measurements. Calculate the sum of ALL the individual
voltages across each resistor in each of the circuits and fill
in the table on the following page.
Kirchhoff’s Laws
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By John Roberts
Circuit 1
Circuit 2
Circuit 3
Circuit 4
Circuit 5
Battery Voltage
Sum of ALL the
individual voltages
across each resistor
1. Compare the battery voltage to the sum of the individual voltages.
2. What do you notice about the two values?
2. Build a parallel circuit that consists of 5 resistances.
a. Using a voltmeter, measure the voltage across the battery
and the potential difference across each individual resistor.
Record the values in the chart below.
b. Build four more circuits and repeat the measurements and
record them.
Circuit
Battery
Voltage
Voltage
R1
Voltage
R2
Voltage
R3
Voltage
R4
Voltage
R5
1
2
3
4
5
What do you notice about the values?
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Kirchhoff’s Laws
3
By John Roberts