Current Electricity

Introduction

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• Special batch for ICSC Class 9
• Encourage joining WhatsApp group, Telegram channel, Facebook page

What is Current Electricity?

• Current Electricity: Flow of electrons
• Static Electricity: Static existence of electrons, accumulation of charges

Cell and Current Flow

• Cell: Direct Current (DC)
  • Example: Pencil battery
  • Flow: Positive to negative
  • Flow direction: Uniform, does not change
• Primary Cell: Cannot be recharged (e.g., pencil battery)
• Secondary Cell: Can be recharged (e.g., inverter battery, mobile battery)

Definition and Unit of Electric Current

• Current: Flow of charge
• Symbol: I (Ampere)
• Charge Symbol: Q (Coulomb)
• SI Unit: Coulomb/second = 1 Ampere
• Charge of an electron: 1.6 × 10⁻¹⁹ Coulomb

Direction of Current

• Two directions:
  • Positive to negative (conventional current)
  • Negative to positive (electron current)

Sources and Instruments

• Sources:
  • Alternating Current (AC)
  • Direct Current (DC)
• Resistance: Obstruction in the flow of electrons
• Rheostat: Device to change resistance

Meters and Connections

• Ammeter: Device to measure current, connect in series
• Voltmeter: Device to measure voltage, connect in parallel

Types of Circuits

• Closed Circuit: Current flows
• Open Circuit: Current does not flow

Insulators and Conductors

• Insulator: Prevents electrical current from flowing (e.g., rubber, plastic)
• Conductor: Allows electrical current to flow easily (e.g., copper)

Ohm's Law

• Ohm's Law: Direct relationship between current and voltage
• Formula: R = V/I
• Unit: Ohm (Ω)

Effects of Resistance

• Resistance depends on material, length, and temperature
• Good conductors have low resistance
• Increasing length increases resistance
• Increasing area decreases resistance

Energy Saving

• Efficient use of energy, environmental protection measures
• Use LED bulbs, to reduce energy consumption

Conclusion

• Inspire students to reduce energy consumption, use good devices
• Share information about Rising Stars