Physics Week 1 Term 2

ELECTRIC CIRCUIT DESCRIPTION

• Definition: An electric circuit is the path or loop through which current can flow.

• Main Components:

  1. Wires: Carry the current through the circuit.

  2. Circuit Components: Devices such as switches, bulbs, motors, resistors, etc. that use current to perform work.

  3. Power Source: Provides electric current; e.g., battery or generator.

OPEN CIRCUIT AND CLOSED CIRCUIT

• Open Circuit: Does not allow the flow of electric current due to issues like a broken wire or an open switch.

• Closed Circuit: The path is complete, allowing current to flow. The circuit closes when a switch is turned on.

SWITCHES IN AN ELECTRIC CIRCUIT

• Function of a Switch: Opens and closes the circuit, controlling current flow.

  • Turning On: Closes the circuit, allowing current to flow (lamp lights up).

  • Turning Off: Opens the circuit, stopping current flow (lamp shuts off).

OHM’S LAW FOR AN ELECTRIC CIRCUIT

• Ohm’s Law: Describes the relationship between voltage (V), current (i), and resistance (R) as:

  • V = iR

• Definitions:

  • Voltage (V): Potential difference measured in Volts (V)

  • Current (i): Measured in Amperes (A), defined as the flow of electric charge.

  • Resistance (R): Measured in Ohms (Ω), the opposition to current flow.

Example Calculation

1. Calculate resistance for a 5A current at 300V:

   • R = V / i = 300V / 5A = 60Ω

2. Calculate current flowing through a resistor of 4Ω under 12V:

   • i = V / R = 12V / 4Ω = 3A

CIRCUIT MODELS

Rope Model

• Explanation:

  • A continuous loop represents the circuit.

  • Movement simulates the flow of electrical current.

  • Participants can feel current flow like components in a circuit (e.g., a lamp).

Water Circuit Model

• Explanation:

  • Water represents electric charge flowing through pipes (wires).

  • A pump functions like a battery pushing water around.

  • A tap can stop the flow similarly to a switch.