3. CURRENT ELECTRICITY
This chapter discusses the fundamental principles of electric current and its behavior in conductors. It covers Ohm's law, the characteristics of conductors, and the impact of temperature on resistance. Additionally, it introduces concepts like current density, electromotive force, and Kirchhoff's rules for circuits, culminating in practical applications such as the Wheatstone bridge.
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What we have learnt
- Current is the flow of electric charge and is measured in amperes.
- Ohm's law states that current is directly proportional to voltage and inversely proportional to resistance.
- Resistivity varies with material and temperature, and conductors like metals have low resistivity compared to insulators.
Key Concepts
- -- Current (I)
- The rate at which electric charge flows past a point in a circuit, measured in amperes (A).
- -- Ohm's Law
- A fundamental principle stating that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance (V = IR).
- -- Resistance (R)
- A measure of the opposition to current flow in an electrical circuit, measured in ohms (Ω).
- -- Resistivity (ρ)
- The intrinsic property of a material that quantifies how strongly it resists the flow of electric current, typically expressed in ohm-meters (Ω·m).
- -- Electromotive Force (emf)
- The energy provided per coulomb of charge by a power source, measured in volts (V).
- -- Kirchhoff's Rules
- A set of two rules for circuit analysis, consisting of the junction rule (the sum of currents entering a junction equals the sum leaving) and the loop rule (the sum of potential differences around any closed loop is zero).
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