Lab: Investigating the relation between potential difference, current, and resistance in a circuit.
Learning Outcome:
1. I can identify the role of each component of a battery.
2. I can verify ohm’s law.
Objective: . In this lab, you will explore the characteristics of electrochemical cell and relate
both resistance and current to potential difference in a series circuit.
Procedure: Visit each station and perform the following.
1. Read the “test information” provided for each station below.
2. Perform the procedure as indicated.
3. Make careful observations for the obtained values of current , voltage and resistance
4. Write a claim as well as the evidence used to support that claim.
Definition of claim and evidence
Example sentence starters
Claim: A statement of what is true or believed to be
It was determined that _________________
true
Evidence: Facts obtained from an experiment that
relate to and support the claim
The evidence that supports this claim
is____________
-----Cut Here----------------------------------------------------------------------------------------------------
Lab: construct a series circuit with resistors to verify ohm’s law
Learning Outcome:
3. I can Construct a series circuit to Observe voltage relationships
4. I can apply ohms law to calculate the value of an unknown resistor through an
experimental lab.
Objective: In this lab, you will construct your own circuit to explore the characteristics of basic
electric concepts.
Also, you will relate both resistance and current to potential difference in a series circuit.
Procedure: Visit each station and perform the following.
5. Read the “test information” provided for each station below.
6. Perform the procedure as indicated.
7. Make careful observations for the obtained values of current , voltage and resistance
8. Write a claim as well as the evidence used to support that claim
Definition of claim and evidence
Claim: A statement of what is true or believed to
Example sentence starters
It was determined that _________________
be true
Evidence: Facts obtained from an experiment that
relate to and support the claim
The evidence that supports this claim
is____________
Page | 1
Station #1: part A) A LEMON BATTERY
– Level 1
Test Information
Part A )
Electrochemical cell require three things (two
electrodes and one electrolyte) .one of the
electrodes has to have a stronger desire for
electrons than the other.
the electricity is not coming
from the lemon but from a chemical
reaction resulting from the differences in electro
negativities between zinc and copper.
Part B)
● Ohm’s law: Current flowing through a resistor
is directly proportional to the potential applied
across it. 𝑉 = 𝐼×𝑅
Current :( I) is the rate of flowing charges
through a conductor .its unit is columb /second
or ampere.(A)
Resistance (R): is the opposition to the motion of
charges through a conductor. Its unit is ohm Ω or
volt /amp.
Observations
● Series connection: Cells are joined end to end in a
series connection. Positive terminal of a cell is
connected to negative terminal of the next cell.
Claim
Learning outcome
achieved:
Resources
Procedure
MATERIALS • lemon • copper
wire • paper clip and voltmeter.
1. Straighten the paper clip,
and insert it and the
copper wire into the
lemon to construct a
chemical cell.
2. Touch the ends of both
wires with your tongue.
3. Read the voltage using a voltmeter connected to
the two metals
4. Insert more wires of both metals and record your
observations.
-
Evidence
Part A )I can identify the role of each component of a battery.
Part B )I can explore the relation between potential difference, current, and
resistance in a circuit.
Part A) https://www.youtube.com/watch?v=GhbuhT1GDpI
Part B) https://phet.colorado.edu/en/simulation/ohms-law
Page | 2
Station #1: A LEMON BATTERY
-Level 2
Test Information
Part A )
Electrochemical cell is made up
of…………………………………….
Part B) PheT simulation
● Ohm’s law: Current flowing through a resistor is directly
proportional to the potential applied across it. 𝑉 = 𝐼×𝑅
Procedure and Model
MATERIALS •
lemon • copper
wire • paper clip
and voltmeter.
1234-
-Current :( I)
is .....................…………………………………………………
……………………its unit is………………….. or ampere.(A)
-Resistance (R): is
……………………………………………………………………
………………….. Its unit is ohm Ω or ……………………..
Observations
Claim
Evidence
Learning outcome achieved:
Resources
-
Part A) https://www.youtube.com/watch?v=GhbuhT1GDpI
Part B) https://phet.colorado.edu/en/simulation/ohms-law
Station 1 Part B: Ohm’s Law
Page | 3
Go to the following: https://phet.colorado.edu/en/simulation/ohms-law and click Play!
1. Determine the direction of the electron flow
2. Complete the table:
Voltage
0.1 V
2.0 V
3.0 V
4.0 V
5.0 V
9.0 V
0.1 V
2.0 V
3.0 V
4.0 V
5.0 V
9.0 V
0.1 V
2.0 V
3.0 V
4.0 V
5.0 V
9.0 V
Current
Resistance
800 Ohms
405 Ohms
40 Ohms
5. Graph your data below. Plot the voltage V as the ordinate (y-axis) and the current I as the
abscissa (x-axis).
6. What kind of relationship did you obtain?
7. Calculate the slope
Page | 4
Phy II 1 – Week 8 – Grade 12
8. What is the physical meaning of the slope of the Current-Voltage graph?
9. Is it possible to decrease the resistance of the wire without changing the material it is made of?
Station #2: -Part A) Construct a series circuit to Observe voltage relationships
Test information
Voltage difference at the battery terminals = the
sum of voltage at each component as voltmeter is
connected parallel at terminals of each
component. However current is the same at any
point because an ammeter is connected in series.
Part B)
Procedure
Material : 3 batteries(1.5 v) ,wires , ammeter, voltmeter,
switch and a fan
1-Label three batteries 1, 2 and 3 with masking tape.
2- Measure the voltage of each separately and record the real
voltage in a table like the one shown.
3- Hold the batteries end to end as below to measure voltage
for combinations.
4-close the circuit to turn on the fan
● Ohm’s law: Current flowing through a resistor
is directly proportional to the potential applied
across it. 𝑉 = 𝐼×𝑅
Current :( I) is the rate of flowing charges through
a conductor .its unit is columb /second or
ampere.(A)
Resistance (R): is the opposition to the motion of
charges through a conductor. Its unit is ohm Ω or
volt /amp.
Observations
Battery
Claim
Voltage (V)
Real
Evidence
Voltage
(V)
Simulation
1
2
3
1+2
1+2+3




Learning outcome
achieved:
Resources:
-
Discuss basic electricity relationships
Analyze the differences between real circuits and the simulated ones
Build circuits from schematic drawings
Use a multimeter to take readings in circuits.
https://phet.colorado.edu/en/simulation/circuit-construction-kit-dc
a. Go to the PHeT web site and use the Circuit Construction Kit simulation (CCK) to do the same
procedure. How does the real world data differ from the simulation? Explain what might cause the
differences.
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
b. Draw what your circuit looks like.
Page | 6
Station 2 Part B: Ohm’s Law
Go to the following: https://phet.colorado.edu/en/simulation/ohms-law and click Play!
1) Look at the switches on the right. Bring the Voltage switch up and down and notice what happens to the fuel cells
in the circuit.
a) What is the maximum number of volts you can get in your circuit? _____________________
b) What is the minimum number of volts you can get in your circuit? _____________________
2) Watch the letters in the equation as you increase and decrease voltage. Which other variable is also affected when
the voltage of a circuit is increased or decreased? Think about this and explain why this is:
_______________________________________________________________________________________________
_______________________________________________________________________________________________
3) Click Reset. Now, increase and decrease the resistance switch. Watch the resistor located in the circuit- describe
what you see as you increase and decrease the resistance. How is this affecting the flow of electrical current (Watch
the equation as well to confirm if you are correct!) Describe the relationship between resistance and current below:
_______________________________________________________________________________________________
_______________________________________________________________________________________________
4)
a) What are the unit, abbreviation and symbol used for Voltage, Resistance and Current?
____________________
5) Click Reset. Practice using the V = IR formula. Then, use the simulator to see if your calculations are correct!
a) If the current in a circuit is 3.2 mA and the resistance of the wire used in the circuit is 250 Ω, what is the voltage
of the fuel cell being used? Use correct units at all times!
Formula: ____________________ Calculation: ____________________ Answer: ____________________
b) If the voltage of the fuel cell used in a circuit is 9.0 V and the resistance of the wire used in the circuit is 560 Ω,
what is the current running through the circuit? Use correct units at all times!
Formula: ____________________ Calculation: ____________________ Answer: ____________________
Page | 7
Station #2: Level 2 –part A ) Construct a series circuit to observe voltage and current relationships with
resistors
Test information
Procedure
Material : 3 batteries(1.5 v) ,wires , ammeter, voltmeter, switch and a known resistor
Voltage difference at the
1-Get a real resistor that is less than 100. Connect the following circuits without the
battery terminals = the
meters.
sum of voltage at each
2-use one multimeter to get your readings by changing the mode and moving it.
component as voltmeter
Record your data in a table like the one below.
is connected parallel at
terminals of each
V
V
component.
V
However current is the
same at any point because
an ammeter is connected
A
A
A
in series.
Observations
Number
of
batteries
1
Voltage
(V)
Claim
Evidence
Current
(A)
2
3




Learning outcome
achieved:
Resources:
-
Discuss basic electricity relationships
Analyze the differences between real circuits and the simulated ones
Build circuits from schematic drawings
Use a multimeter to take readings in circuits.
https://phet.colorado.edu/en/simulation/circuit-construction-kit-dc
c. Go to the PHeT web site and use the Circuit Construction Kit simulation (CCK) to do the same
procedure. How does the real world data differ from the simulation? Explain what might cause the
differences.
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
d. How are current and battery voltage related? What would be the shape of the graph?
………………………………………………………………………………………………………………
…………………………………………………………………………………………………………..…..
e. Practice using the voltmeter and realistic ammeter in several circuits. Describe how using a voltmeter is
different from using an ammeter. Repeat the whole steps using a resistance coil of unknown value.
………………………………………………………………………………………………………………
…………………………………………………………………………………………….………………..
Page | 8
Station #3: -Construct a series circuit to Verify ohm’s law.
List of Components
(Variable DC Power supply - 1kΩ resistor (Color code Brown, Black, Red, Gold) - Breadboard Connecting wires (Jumper wires) - Ammeter)
Test information
Procedure
● Ohm’s law: Current
flowing through a resistor is
directly proportional to the
potential applied across it. 𝑉
= 𝐼×𝑅
Current :( I) is the rate of
flowing charges through a
conductor .its unit is columb
/second or ampere.(A)
Resistance (R): is the
opposition to the motion of
charges through a conductor.
Its unit is ohm Ω or volt
/amp.
.
1. Drag a resistor over to the circuit board and change the resistance
to your value of choice.(resistance coil)
2. Attach a wire to each end of the resistor.
3. Attach an ammeter (measures current in amps) to the free end
of one wire.
4. Attach a battery to the free end of the other wire.
5. Connect the free end of the ammeter to the free end of the
battery with one more wire.
6. Drag a voltmeter to the circuit board. Connect the red probe to
one end of the resistor and the black probe to the other end of
the resistor.
7. Use the power supply to change the voltage from 1 to 10
volts. This should change the current in the wire. Record the
current in Table 1.
8. Fill in the appropriate scale on the y-axis on Graph 1. Since
current varies with voltage, current is the independent variable.
Fill in your y-axis scale according to your current values.
9. Plot the voltage and current on Graph 1.
Observations
Claim
Evidence
Current, I (amps)
Graph 1. Graph of voltage vs. current
Voltage,V(volts)

Learning outcome:

Resources:
-
I can verify that current is inversely proportional with resistance and directly proportional
with voltage difference.
Build circuits from schematic drawings
https://phet.colorado.edu/en/simulation/ohms-law
Page | 9
Conclusions:
1. What is the slope of your graph? Is it positive or negative? What does this indicate about the relationship
between voltage and current?
2. What does this slope represent in the Ohm’s Law formula?
3. Use your answers from 1 and 2 to calculate the resistance. Does this match the actual resistance
you chose when you set up your circuit?
4. Explain in words the relationship between resistance and current. (i.e. “When resistance increases,
current…”)
5. If you doubled the resistance, but kept the same voltages, how would the graph of currents look
different? Describe how the slope has changed. Draw a rough sketch on the graph.
Page | 10
Station 4
Ohm’s Law Lab Report
Ohm’s law is the fundamental law of Electrical Engineering. It relates the current
flowing through any resistor to the voltage applied to its ends. According to the
statement: The current flowing through a constant resistor is directly proportional
to the voltage applied to its ends. .
Objective:
To verify that voltage and current are directly proportional using a 1kΩ resistor.
List of Components





Variable DC Power supply
1kΩ resistor (Color code Brown, Black, Red, Gold)
Breadboard
Connecting wires (Jumper wires)
Ammeter
Circuit Diagram
Setup the circuit diagram as shown below:
Steps
1.
2.
3.
4.
5.
6.
Implement the circuit on the breadboard as shown in circuit diagram.
Initially set the VDC supply to 0 V and note the current on ammeter.
Increase the voltage to 1 V, observe the ammeter and note the readings.
Repeat the above step for 2 V, 3V … 10 V.
Plot a graph for measured readings.
Compare the plot with theoretical calculations.
-Observation table (Experimental values)
-The theoretical calculations are achieved from the formula, V = IR.
Voltage (v)
0
1
2
3
4
5
6
7
8
9
Current (mA)
Experimental
Voltage (v)
Current (mA)
theoretical
0
1
2
3
4
5
6
7
8
9
Page | 11
Graph
The real (practically calculated – red color) vs the theoretical values (blue) are
plotted on the graph. While most theoretical values are identical to practical
values, one might note a difference of red dot for 2.99 mA and 6.99 mA.
Current, I (amps)
-Plot a Graph of voltage vs. current
Voltage,V(volts)
-conclusion:
………………………………………………………………………………………………
………………………………………………………………………………………………
………………………………………………………………………………………………
……………………………………………………………………………………………….
Basic Questions for Ohm’s Law Lab Report
1- What is Variable DC supply?
2- What is ammeter?
3- What is the resistor, and what is resistor color coding?
4- Why practical results are different from theoretical results?
Page | 12
Extension: Multiple Resistors
1. Now modify your circuit so that you have two resistors of the same resistance in series (so that the
same current is flowing through both resistors) as illustrated below.
−
+
Keep the voltage the same. What is the new current?
2. What is the total resistance of the resistors in series?
Page | 13