IGCSE Physics Ch 3 Electricity (Part 1 of 3) - Cambridge CIE

Explore electrostatics fundamentals, including conductors and insulators, charging methods (rubbing, contact, induction), and the earth's electric properties, then introduce charge Q, electric fields, and the forces between charged bodies.

Explore how friction charges objects, producing positive and negative charges; like charges repel, opposite charges attract, and the electrostatic force grows as charge increases and distance decreases.

Identify conductors and insulators by free electrons and dryness. Explain earthing as a discharge that moves electrons between a rod and earth, with negative or positive charges.

Explore three methods of charging objects: charging by rubbing, charging by contact, and charging by induction, including electron transfer, polarization, and earth grounding steps.

Express charge as the quantity of charge Q, a measurable amount formed by electron transfer; use the coulomb as a larger unit to measure charge, including negative charges.

Explore the electric field around charged plates and spheres, shown by field lines; learn how a test charge moves from positive to negative and how fields differ.

Explore the electrostatic force on a positively charged particle moving in an electric field between opposite plates, tracing its straight entry, curved trajectory toward the negative plate, and straight exit.

Explore the three pillars of electricity—voltage, current intensity, and resistors—and analyze circuits in series and parallel, including electric energy, power, and charge.

Voltage is the energy per charge moving from the battery to the bulb in a simple circuit, including single-component, series, and parallel arrangements, with v = e/q.

This lecture explains how, in series, the battery's voltage divides between bulbs while in parallel, each bulb receives the full voltage.

Measure voltage by connecting the voltmeter in parallel with the battery or component, ensure correct polarity, and use high resistance so parallel components share the same voltage.

Explore electric current intensity I, defined as charge flow per second Q/t, and compare series versus parallel circuits, including how current remains the same in series and divides in parallel.

Explore how wire resistance depends on length, cross-sectional area and material, using R = ρL/A; thicker wires reduce resistance, and very short leads can be neglected.

Explain how a bulb's resistance affects current in a simple battery circuit and how series increases and parallel decreases total resistance for two resistors.

Master the rules for voltage, current, resistance, and power in series and parallel circuits, and apply Ohm's law to past-paper questions.

Explore the second part of electric current and circuits, defining current, comparing AC and DC, examining the variable resistor, ohms law, circuit symbols, potential meter, and vehicles as essential tools.

Explain the concept of electric current by contrasting electron flow from negative to positive with the conventional current from positive to negative, and define current as charge per unit time.

Explore how electric current causes heating and lighting in a filament, and the magnetic effect around wires that forms electromagnets; also examine chemical changes from electrolysis.

Compare direct current, flowing in one direction from cells or batteries, with alternating current, which changes direction and is produced by AC generators.

Explain the variable resistor and rheostat, including the coil, insulating cylinder, and slider, and show how slider position changes resistance and bulb brightness in a circuit.

Explore electric symbols for circuit components, including connect/disconnect rules, switches, cells and power supplies, and common parts such as resistors, diodes, meters, relays, light-emitting diodes, transformers, and more.

Verify ohm's law by measuring voltage and current in a resistor circuit, plot I versus V, and derive resistance from the slope.

Explains how a three-end potentiometer, a type of variable resistor, splits a coil into two series resistors via slider, varying the voltmeter voltage and demonstrating voltage division from the battery.

Explore electricity at home installation, including mains electricity and how to connect appliances safely, common problems, and the potential dangers of electricity.

Explore how electricity travels from power stations to homes, forming complete circuits with plugs and sockets so a bulb lights when the live brown and blue wires close the circuit.

Explain how large current risks heating wires and electric shocks when live touches metal casing, and how fuses protect appliances by melting at higher currents, with values near appliance current.

Explain how a live wire touching metal casing can drive current through the body to earth, and how earth wiring, fuses, circuit breakers, and double insulation protect safety.

Compare parallel and series appliance connections, noting voltage distribution, current, and power from the mains, and how in parallel one failure doesn't stop others while in series all fail.

Explore the dangers of electricity, including electric shocks from damaged insulation, and the fire risks from overheating wires when extremely high currents pass.