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I/GCSE Physics Question Analysis Topic: Chapter 2: Electricity - Energy and Voltage in Circuits (Part 1)
For I/GCSE Physics, you should know:
Let's begin the IGCSE Physics Chapter 2 sub-topic on "Energy and Voltage in Circuits".
Effect of Changing Resistance on Current:
- When the resistance in a circuit is increased, the current decreases.
- This is due to Ohm's law, which states that the current is inversely proportional to the resistance in the circuit.
Variation of Resistance in Components:
Light-Dependent Resistors (LDRs): - The resistance of an LDR decreases as the illumination on the component increases.
- This makes LDRs useful for light-sensitive applications, such as automatic lighting controls.
Thermistors: - The resistance of a thermistor decreases as the temperature increases.
- Thermistors are used in temperature-sensing applications, such as in electronic devices to monitor and regulate temperature.
Indicating the Presence of Current: - Lamps and Light-Emitting Diodes (LEDs) can be used to indicate the presence of current in a circuit.
- When current flows through these components, they emit light, providing a visual indication of the circuit's operation.
Choosing Series or Parallel Circuits: - Series Circuits:
- In a series circuit, the components are connected one after the other, forming a single path for the current.
- Series circuits are commonly used for domestic lighting, as a failure in one component (e.g., a light bulb) will cause the entire circuit to be interrupted.
- Parallel Circuits:
- In a parallel circuit, the components are connected to the same set of terminals, allowing current to flow through multiple paths.
- Parallel circuits are often used in household wiring, where individual appliances or lights can be turned on or off without affecting the rest of the circuit.
Current in Series Circuits: - In a series circuit, the current is the same through all the components, as there is only a single path for the current to flow.
- The current in a series circuit depends on the applied voltage and the total resistance of the circuit.
Variation of Current with Voltage: - Wires: The current is directly proportional to the voltage, following Ohm's law.
- Resistors: The current is directly proportional to the voltage, again following Ohm's law.
- Metal Filament Lamps: The current increases with voltage, but the relationship is non-linear due to the change in resistance of the filament as it heats up.
- Diodes: The current only flows in one direction (forward bias) and exhibits a non-linear relationship with voltage.
To investigate the relationship between current and voltage, you can set up experiments with various components, such as wires, resistors, metal filament lamps, and diodes. By measuring the current and voltage across these components, you can observe and analyze the different behaviors.
Work hard for your I/GCSE Physics examination!
End of analysis. Great!
