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dc circuits resistance
A LevelPhysics~3 min read
Overview
This lesson introduces the fundamental concepts of direct current (DC) circuits, focusing on resistance and Ohm's Law. We will explore how resistance impedes current flow and how voltage, current, and resistance are interconnected in simple circuits.
1. Introduction to Electric Current and Potential Difference
Electric current, denoted by **I**, is defined as the rate of flow of electric charge. Mathematically, it is given by the formula **I = Q/t**, where Q is the charge in Coulombs (C) and t is the time in seconds (s). The unit of current is the Ampere (A), which is equivalent to one Coulomb per second....
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Key Concepts
- Electric Current (I): The rate of flow of charge (coulombs per second), measured in Amperes (A).
- Potential Difference (V): The energy transferred per unit charge between two points, measured in Volts (V). Also known as voltage.
- Resistance (R): A measure of how much an object opposes the flow of electric current, measured in Ohms (Ohms).
- Ohm's Law: States that for an ohmic conductor at constant temperature, the current flowing through it is directly proportional to the potential difference across it (V = IR).
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Exam Tips
- →Always state Ohm's Law (V=IR) clearly in your answers and define all symbols used.
- →Be able to sketch and interpret V-I graphs for ohmic conductors (straight line through origin) and non-ohmic conductors (e.g., filament lamp, diode).
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