Lesson - Understanding Current Electricity and Ohm's Law
Lesson Duration - 100 minutes
Content:
Define Ohm’s Law;
Understand relationship among Voltage (V), Current (I), Resistance (R);
Plot and analyze I-V graphs;
Solve calculation problems using V=IRV = IRV=IR.
Communication:
Use key scientific vocabulary (voltage, current, resistance, proportionality, conductor, linear, ohm) correctly in discussion and writing.
Use sentence starters and peer explanation to support English usage.
Cognition:
Formulate hypotheses, conduct experiments, analyze data, draw conclusions.
Transfer understanding from lab to simulation and real-world contexts.
Culture:
Relate safety and energy efficiency of electrical circuits to students’ own homes and community.
Resistors (fixed, variable, LDR)
Voltmeter, Ammeter, Rheostat, Switch
Connecting wires, Power supply
Graph paper, Calculator
Simulation tool: Circuit Construction Kit: DC (PhET)
Videos (Don’t Memorise, FuseSchool, YouTube Physics channels)
Purpose: Activate background knowledge & reduce language anxiety.
🎥 Pre-Class Video (3–4 min): Share via Padlet wall
📝 Task for Students:
Take the Edcafe Quiz
Write down 3 keywords they understood (in English).
Write 1 question they still have (in Tamil/English).
📩 Submission: Students post responses to the padlet wall.
“Yesterday, you did the EdCafe quiz. What were some new words or ideas you saw?”
“Which question was most difficult for you? Why?”
👉 Purpose: Activates memory + acknowledges effort.
The teacher shows 1–2 sample questions from the pre-lesson quiz.
Ask:
“What did most of you answer here?”
“Why do you think this is correct / not correct?”
Collect ideas on the board → highlight keywords (voltage, current, resistance).
👉 Purpose: Shared brainstorming and gentle correction.
(Before showing the video, guide them with open-ended questions):
“When we increase the number of cells in a circuit, what might happen to the current?”
“Why do some bulbs glow brighter than others?”
“What could stop current from flowing easily?”
“What might be the relationship between voltage, current, and resistance?”
👉 Purpose: Students predict and connect their quiz knowledge to real-world circuits.
“Great ideas! Let’s check if scientists explain it the same way.”
Play short intro video (Ohm’s Law explanation).
Follow immediately with EdCafe quiz activity (to check predictions).
📝 Sentence Starters for Students
“I remember from yesterday that …”
“I think the answer is … because …”
“In the quiz, I saw the word … which means …”
Purpose: Hands-on investigation of the current–voltage relationship.
🔧 Lab Task (Groups of 4):
Vary the voltage and measure the current using a voltmeter/ammeter.
Record data in a table.
📊 Groups plot I–V points on graph paper/whiteboard.
Answer post practical Quiz
Instructions for Students:
Answer briefly in 1–2 sentences or by drawing/labelling where needed.
Why should we switch off the circuit immediately after taking a reading?
If the ammeter does not deflect, what could be the reason?
How can you fix the issue if the ammeter does not deflect?
Apparatus & Connections
Is it a good idea to use very lengthy wires in the circuit? Why / why not?
Instead of dry cells, what alternative power source can we use?
Draw the circuit diagram for Ohm’s Law experiment and label all components.
How should the ammeter be connected in the circuit?
How should the voltmeter be connected?
What is the function of the rheostat in this experiment?
What will happen to the ammeter reading and the associated voltmeter reading if you increase the applied voltage?
Record the values in an I vs V data table.
Plot the I–V graph.
Find the gradient of the graph. What physical quantity does this gradient represent?
Is this quantity equal to the resistance of the resistor? Explain briefly.
Find the resistance across the voltmeter (use your data to support your answer).
🗣 Group Presentations: Share graphs & findings.
👩🏫 Teacher Formalises: V=IRV = IRV=IR.
📖 Word Bank (display on site):
Term Meaning
Voltage (V) Electrical pressure
Current (I) Flow of electrons
Resistance (R) Opposition to the current
Ohm (Ω) Unit of resistance
Proportional Direct relationship
Linear Straight-line graph
📝 Sentence Starters:
“Our graph shows that current … when voltage …”
“Ohm’s Law means that …”
🎥 Reinforcement Video (2–3 min): Embed short animation.
Term Meaning
Voltage (V) Electrical pressure
Current (I) Flow of electrons
Resistance (R) Opposition to current
Ohm (Ω) Unit of resistance
Proportional Direct relationship
Linear Straight-line graph
📝 Sentence Starters:
“Our graph shows that current … when voltage …”
“Ohm’s Law means that …”
🎥 Reinforcement Video (2–3 min): Embed short animation.
🌐 PhET Simulation (Embed): Students adjust V & R → record outcomes.
Students follow the task sheet given and do PhET simulations and find the V vs I relationship.
👥 Worksheet Prompts:
“What happens if both V & R increase?”
“What does a non-Ohmic conductor look like?”
🖼 Poster Task: Groups design poster → “Safe electricity use at home.”
Objective:
Construct and analyze two DC circuits using the PHET Circuit Construction Kit. You will work with resistors, bulbs, and a power source, measuring current and voltage at various points in the circuit.
Battery: 10V DC
Resistors: 5Ω, 10Ω, 15Ω
Bulbs: 2
Ammeter and Voltmeter
Series Circuit:
Connect the 5Ω, 10Ω, and 15Ω resistors in series.
Place the bulbs after the resistors.
Measure total current and voltage across the battery and each component.
Parallel Circuit:
Connect the 5Ω and 10Ω resistors in parallel; then add the 15Ω resistor in series with them.
Place the bulbs in the circuit.
Measure total current and voltage as before.
Measure current and voltage for both series and parallel circuits.
Analyze:
How does current and voltage behave in both configurations?
What happens when you change the resistance or battery voltage?
Deliverables:
Screenshots of your circuits.
Record and explain your current and voltage measurements.
❓ Comprehensive Quiz (7–10 Qs): Rapid Question fire - teacher randomly call students to answer questions which ensures consolidation
What is the formula of Ohm’s Law?
If voltage increases and resistance stays the same, what happens to the current?
What is the unit of resistance?
True or False: In a series circuit, the current is the same at all points.
If a 10V battery is connected to a 5Ω resistor, what is the current?
What happens to total resistance when resistors are added in parallel?
Name the device used to measure current in a circuit.
If current is 2A and resistance is 6Ω, what is the voltage?
True or False: In a parallel circuit, the voltage across each branch is different.
What happens to the current if resistance doubles and voltage stays the same?
Purpose: Reinforce and extend learning.
📐 Solve 3 calculation problems.
🎙 Record a voice note explaining one solution (Tamil + English mix allowed) → Padletwall
🌐 Extension: Use PhET at home to test non-Ohmic conductors.
🖊 Reflection Journal: Write 3 sentences using new vocabulary (voltage, resistance, proportionality, ohm).
A 12V battery is connected to a resistor in a circuit, and the current measured is 4A.
Calculate the resistance of the resistor.
Then, if the battery voltage is increased to 18V, what will the new current be if the resistance remains the same?
Hint: Use Ohm's Law: V=IRV = IRV=IR
Two resistors, 6Ω and 12Ω, are connected in series across a 24V battery.
Find the total current in the circuit and the voltage drop across each resistor.
Hint: Use the total resistance for series resistors:
Rtotal=R1+R2
A circuit consists of a 9V battery, a 3Ω resistor, and an unknown resistor connected in parallel. The total current in the circuit is 6A.
Find the value of the unknown resistor.
Hint: Use the formula for parallel resistors:
1/Rtotal = 1/R1 + 1/R2
In a series circuit with a 10Ω resistor and a 20Ω resistor, connected to a 30V battery, the current measured is 2A.
Find the power dissipated by each resistor.
What is the total power consumed by the circuit?
Hint: Use the formula for power: P=VI , V=IR
A circuit with a 15V power source contains three resistors: 5Ω, 10Ω, and 15Ω connected in parallel.
Find the total current supplied by the battery.
Then, calculate the voltage drop across each resistor.
Hint: For parallel resistors, use:
1Rtotal=1R1+1R2+1R3