Questions and Answers
Which of the following is a unit of electric current?
What is the relationship between power, current, and voltage?
Mains electricity is supplied as alternating current (a.c.) only.
False
What does LDR stand for?
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The SI unit of charge is the ______.
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Explain the effect of resistance on current in a circuit.
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What happens when unlike charges are brought together?
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How is electric current defined?
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Match the following units with their definitions:
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The equation for energy transferred is: energy transferred = charge × ______.
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Study Notes
Units of Measurement
- Common units include ampere (A), coulomb (C), joule (J), ohm (Ω), second (s), volt (V), and watt (W).
- Ampere (A) measures electric current with the equation: 1 A = 1 C/s.
- Coulomb (C) quantifies electric charge; 1 C = 1 A·s.
- Joule (J) represents electrical energy; equivalently, 1 J = 1 C·V = 1 W·s.
- Ohm (Ω) indicates electrical resistance; defined as 1 Ω = 1 V/A.
Mains Electricity
- Insulation, double insulation, earthing, fuses, and circuit breakers enhance safety in domestic appliances.
- Current flowing through a resistor generates heat through electrical energy transfer, applicable in various household devices.
- Power relationship: P = I × V, allowing appropriate fuse selection based on energy requirements.
- Energy transferred is calculated with E = I × V × t, integrating current, voltage, and time.
- Mains electricity uses alternating current (a.c.) as opposed to direct current (d.c.) from cells or batteries.
Energy and Voltage in Circuits
- Series circuits are preferred for certain applications like domestic lighting due to their specific current characteristics.
- In series circuits, current is influenced by applied voltage and overall component resistance.
- Voltage-current behavior varies in different materials: wires, resistors, filament lamps, and diodes, observable via experiments.
- Resistance changes impact current flow qualitatively; understanding this is crucial for circuit design.
- Light-dependent resistors (LDRs) vary resistance with light level; thermistors change resistance based on temperature.
- Indicators like lamps and LEDs show current presence in circuits.
- Voltage, current, and resistance relationship: V = I × R, establishes foundational circuit analysis.
- Charge flow: Q = I × t links charge, current, and time; essential for understanding current flow dynamics.
Electric Charge
- Identify electrical conductors (metals) and insulators (plastics) based on common examples.
- Investigate charging methods of insulating materials through friction.
- Electrostatic charges arise from electron transfer: positive from loss and negative from gain.
- Charges exhibit attraction between unlike charges and repulsion among like charges; key in electrostatic interactions.
- Electrostatic phenomena explained via electron movement principles.
- Recognize risks associated with static electricity, especially in fueling operations to prevent ignitions.
- Applications of electrostatic charges include photocopying and inkjet printing technologies, exploiting charge manipulation.
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Description
Test your knowledge of the electricity section in the International GCSE Physics curriculum. This quiz covers essential topics such as units, mains electricity, energy and voltage in circuits, and electric charge, preparing you for the upcoming examination in June 2025.
