Lesson 5: Parts of a Circuit

Review Questions

  • Question 1: A car uses 100,000J of chemical energy, with 38,000J transformed into kinetic energy and 2000J into energy for lights, radio, and battery recharge. Calculate the energy wasted as heat and sound.
  • Question 2: What occurs when a glass rod is rubbed against fur, resulting in a negative charge?
    • a) Electrons travel from the fur to the rod
    • b) The fur is left neutral
    • c) Electrons travel from the rod to the fur
    • d) Protons are removed from the rod
  • Question 3: List the three different ways objects can acquire an electric charge.
  • Question 4: Identify the unit of energy.

Learning Intentions

  • Understand key terms in electric circuits:
    • Voltage
    • Current
    • Power
    • Resistance

Success Criteria

  • Understand the concept of a circuit, including open and closed circuits.
  • Define voltage, current, and resistance, including their symbols and units.

Electric Vocabulary

  • Key terms related to electricity.

Current

  • Definition: The 'flow' of charge, representing the number of electrons passing a point per second.
  • Unit: Amperes (A)
  • Measurement Tool: Ammeter

Voltage

  • Definition: The amount of energy each electron possesses.
  • Unit: Volts (V)
  • Measurement Tool: Voltmeter

Resistance

  • Definition: The opposition to the flow of current in a circuit (analogous to rocks in a river).
  • Unit: Ohms (Ω)
  • Measurement Tool: Ohmmeter (using a resistor)

Basic Requirements for Electricity Usage

  • A closed pathway or circuit for the current to flow.
  • Good electrical conductors (e.g., metal, graphite) for the current to flow through.
  • An energy source (e.g., power station, generator, or battery) to drive the current.
  • Components within the circuit that utilize the energy to perform a function (e.g., light bulb, motor, computer).

Circuit Diagrams

  • Scientists use circuit symbols for consistency and efficiency.
  • Wires are represented as straight lines, not necessarily reflecting the actual lengths.

Series Circuits

  • Definition: A circuit where all components are connected in a single loop.
  • Example: A circuit with two lamps connected in series.
  • Diagrams: Always drawn with straight lines.

Parallel Circuits

  • Definition: A circuit with junctions where the current can split (point A) or join (point B), providing multiple paths.

PHET Simulation

  • Create a series circuit with the following components:
    • Battery: 9 Volts
    • Resistor: 4 Ohms
    • Light bulb: 4 Ohms
    • Closed switch
    • Connecting cords