A 2-day foundational physics sequence on electric circuits, covering atomic electron movement, hardware anatomy, closed loops, and Ohm's law with self-guided sub work.
Sequence: Current Connections • Day 1: Loop Launch Page 2 of 2
Current must go THROUGH the filament between both contacts!
Now that we know the parts, let's solve the famous 1-wire puzzle! Slide 4 of 9
The Hands-On Puzzle Slide 5 of 9
Can you light a bulb with only 1 wire?
You hold 1 battery, 1 light bulb, and 1 strip of wire in your hands.
What do you think happens if wire only touches one side?
👍 YES, it lights!
👎 NO, it stays dark!
1.5V + ? Wire connects (+) only • no bottom path!
Turn to your neighbor: Why won't this work based on what we just learned? Answer next! →
The Fundamental Law Slide 6 of 9
1 Wire Alone = Bulb STAYS DARK! ❌
Rule #1: Electricity must have a complete loop!
No Complete Circle = Zero Current Flow!
Electrons cannot pile up at a dead end. They must leave the battery, go through the bulb filament, and have an unbroken return path back to the other terminal!
- Both Contacts Connected = Closed Circuit = LIGHT!
The word Circuit comes from the Latin word for circle! Slide 6 of 9
Controlling the Loop Slide 7 of 9
Open vs. Closed Circuits: What a switch really does
OPEN CIRCUIT GAP PRESENT
❌ Switch is OPEN • Path is cut by air (insulator) • OFF
CLOSED CIRCUIT CONNECTED
✅ Switch is CLOSED • Metal touches metal • ON
Now let's apply this in our hands-on partner lab! Slide 7 of 9
Partner Practice Lab (12 Mins)
Slide 8 of 9
Open Your Loop Builders Worksheet!
1
Parts 1 & 2
Atomic foundation & naming conductors vs insulators.
2
Part 3
Loop Detectors: Inspect Circuits A, B, and C for hidden gaps.
3
Part 4
Wire Router: Connect both contacts of the bulb back to battery.
Golden test: Can you trace a complete pencil line through the wire, through the bulb, and back home?
Work collaboratively with your partner • raise hands if stuck Slide 8 of 9
Day 1 Mastery Check Slide 9 of 9
Day 1 Complete! 💡
Today's Big Win:
You discovered that electricity is not magic. It is electrons flowing through an unbroken closed loop connecting both contacts of a bulb to both terminals of a battery!
Tomorrow on Day 2:
You will complete a self-guided investigation on Push (Voltage), Flow (Current), and Squeeze (Resistance) with full guided notes!
Ticket to Leave: Loop Check Exit Ticket
Complete your 1-page exit ticket individually and submit it before the bell!
Turn in exit ticket at the door • Great work today! Day 1 Complete!
Early Finishers
Early finishers should complete the "Challenge Scenario" on the back of their notes packet, reviewing the danger of zero-resistance short circuits.
Sequence: Current Connections • Day 2 Sub Plan (40 Min) Neighboring Physics Teacher: Rm 204 Page 1 of 1
3
Concept 3: Resistance (R) — The SQUEEZE
Unit: Ohms (Ω)
What It Is: Any obstacle or narrow constriction that fights and slows down the flow of electrons. Light bulb filaments are made of microscopically thin wire that creates high resistance.
Energy Transformation: The friction of electrons crowding through the filament converts electrical energy directly into thermal heat and glowing light!
💡 Core Rule: More Resistance = Harder for electrons to pass = Slower Current!
🤏 Water Twin: Pinched Hose
If you step on a garden hose or make the pipe thinner, water has to fight through the narrow pinch. That friction and constriction is electrical Resistance!
✍️ Checkpoint 3: Why do we want the light bulb filament to have high resistance, but connecting wires to have almost zero resistance?
4 Concept 4: Putting It Together (Ohm's Relationship)
Push harder (add a battery) with the same resistance → Current speeds up and bulbs glow brighter!
Rule B: Squeeze Up → Flow Down!
Add more obstacles (extra bulbs in a row) with the same push → Current slows down and bulbs glow dimmer!
Concrete Example: A 12V push against a 4Ω squeeze produces 12 ÷ 4 = 3 Amps of flow. If you double the push to 24V with the same 4Ω, 24 ÷ 4 = 6 Amps (Double the flow!).
5 Concept 5: Circuit Scenario Predictions
Use Rule A or Rule B above to explain what happens to Current and Bulb Brightness:
Scenario 1: You add a second identical battery to your circuit. What happens to the bulb's brightness, and why?
Hint: Did the Push increase, or the Squeeze increase?
Scenario 2: You add a second light bulb in the same loop. What happens to the brightness of both bulbs, and why?
Hint: Did you add more Push, or more Squeeze?
Challenge Scenario: A wire connects directly from (+) to (−) without any light bulb (Zero Resistance!). Why does the wire get dangerously hot?
Sequence: Current Connections • Day 2 Guided Notes Page 2 of 2
Full Credit (2 pts): Flow (Current) equals Push (Voltage) divided by Squeeze (Resistance) — or "Voltage pushes electrons, Resistance fights them, and Current is the resulting speed of flow."
Sequence: Current Connections • Day 2 Master Answer Key Confidential Teacher / Sub Resource Page 1 of 1
