Resistor Flex

Control the Flow Like a Pro

Gaelen Guzman

2025-03-18

Safety first!

Electricity can be dangerous!

Always do this with an adult!

What is electricity??

Electricity is made when charged particles move


Every atom is made of particles

  • Protons →
  • Electrons →
  • Neutrons

Electricity is made of moving charged particles

  • high potential → low potential
  • Transports energy that can perform work

We can pretend electricity is like water

  • high potential → low potential
  • Transports energy that can perform work

How does electricity do stuff?

  • Voltage → Volts (V)
  • Current → Amps (A)
  • Resistance → Ohms (Ω)

Example of a load: LED

  • Light Emitting Diode
  • Can only handle a small amount of current!
  • /+ and - matters!

Hands on! Circuit #1

Components:

  • Coin battery →
  • LED →

Hands on! Circuit #1

Components:

  • Coin battery →
  • LED →

Breadboards make testing complicated circuits easy!

Hands on! Circuit #2

Components:

  • Breadboard
  • 5 V power supply →
  • LED →
  • Resistor →

Hands on! Circuit #2

Components:

  • Breadboard
  • 5 V power supply →
  • LED →
  • Resistor →

Hands on! Circuit #3

Components:

  • Breadboard
  • 5 V power supply →
  • LED →
  • Resistor →
  • Button →

Hands on! Circuit #3

Components:

  • Breadboard
  • 5 V power supply →
  • LED →
  • Resistor →
  • Button →

Hands on! Circuit #4

Components:

  • Breadboard
  • 5 V power supply →
  • LED →
  • Resistor →
  • LDR →

Hands on! Circuit #4

Components:

  • Breadboard
  • 5 V power supply →
  • LED →
  • Resistor →
  • LDR →

Types of circuits

Series

Only one path for the current to go.

Parallel

Multiple ways to get back to the negative terminal.

How does current behave in a series circuit?

How does current behave in a parallel circuit?

Hands on! LED Circuit #5

Components:

  • Breadboard
  • 5 V power supply →
  • 4x LED →
  • 220 Ω Resistor →

Hands on! LED Circuit #5

Components:

  • Breadboard
  • 5 V power supply →
  • 5x LED →
  • 220 Ω Resistor →

Discussion: Why doesn’t this one work??

Hands on! LED Circuit #6

Components:

  • Breadboard
  • 5 V power supply →
  • 4x LED →
  • 220 Ω Resistor →

Hands on! LED Circuit #6

Components:

  • Breadboard
  • 5 V power supply →
  • 4x LED →
  • 220 Ω Resistor →

Discussion: Why does this one work??

Transistors: Electrical switches

OFF if no current delivered to the Base

ON when even a tiny bit of current flows to the Base

Hands on challenge: Night light

Components:

  • Breadboard
  • 5 V power supply →
  • LED →
  • 220 Ω Resistor →
  • 100 kΩ Resistor →
  • LDR →
  • Transistor →
  • Jumper cables

Electrons go the opposite way? Confusing!

Benjamin Franklin didn’t know what electrons were: he took a guess about which direction things were moving, and he happened to guess wrong!

Electrons go the opposite way? Confusing!

By convention, we always pretend that a charge is going around the circuit – even though it’s just imaginary, it doesn’t change how the circuit works.

Brainstorm!

What can we invent?

So many types of components!

  • Batteries
  • Resistors
  • LEDs
  • Light-dependent resistors
  • Buttons
  • Transistors
  • Motors
  • Valves
  • Cameras
  • Microphones
  • Solar panels
  • Temperature sensors
  • Air quality sensors
  • Magnetic field sensors
  • Moisture sensors