Flash_cards_P2_Electricity_Revision_AHY

Electricity Revision Flashcards

Date: 12/25/2024

Standard Circuit Diagram Symbols

  • Circuit diagrams use standard symbols; students should draw and interpret these.

Energy Sources in Circuits

  • Cells/batteries serve as alternatives to mains electricity.

  • Symbols: Cell, Battery.

Analogy for Electric Charge

  • Moped riders = electric charge (electrons)

  • Pizza = electrical energy, Pizzeria = energy source, House = bulb/device

  • 1 rider per second = 1 ampere. Increased speed means increased current.

  • Potential difference = more pizzas.

Common Circuit Symbols

  • I: Cell, Lamp, Switch, Wires.

Key Equations

  • Q = It

  • V = IR

  • R_total = R1 + R2

  • E = Pt

  • P = VI

  • P = 12R

  • E = QV

Current Measurement

  • Current = rate of electric charge flow, measured in coulombs (C).

  • Ammeter in series; 1 A = 1 C/s.

  • Formula: I = Q/t.

Ohm’s Law

  • V = I × R.

  • Voltage and current are proportional; resistance is constant unless temperature changes.

Formula Triangle for Resistance

  • To find I, V, or R:

    • I = V/R.

Factors Affecting Resistance

  • Material, Length, Thickness, Temperature.

  • Longer wire = higher resistance; thicker wire = lower resistance.

Investigating Resistance

  • Required setup: Switch, Ammeter, Ruler, Test wire, Voltmeter.

Temperature and Resistance

  • Metals are ohmic conductors; resistance varies in non-ohmic conductors.

I-V Characteristics Investigation

  • Setup: Battery, Variable resistor, Ammeter, Voltmeter.

I-V Graphs

  • Copper allows higher current than constantan; steeper gradient = lower resistance.

Ohmic Conductors

  • I-V characteristics of various resistors.

I-V Characteristics for Filament and Diodes

  • Filament lamps display changing resistance with a curved I-V graph.

Sensors Investigation

  • Components: Light Dependent Resistors (LDRs), Thermistors.

Application in Sensor Circuits

  • Series components share potential difference; resistance changes with environment.

Types of Circuits

  • Series and Parallel; requires drawing cells, wires, and bulbs.

Measuring Current in Circuits

  • Series: Current constant (2A). Parallel: Shared among components.

Measuring Voltage

  • Voltmeter connections: Series shares voltage, Parallel maintains same voltage.

Series Circuit Voltage Sharing

  • Example: 3V shared among components.

Parallel Circuit Voltage Consistency

  • Voltage remains constant at 3V.

Practical on Resistance Investigation

  • Setup: Two resistors in series and parallel.

Resistance Graphing

  • Data gathering for series vs parallel resistance.

AC vs DC Current

  • DC = constant voltage; AC = changing direction, 50 Hz in UK mains.

AC Frequency Characteristics

  • Measured with oscilloscopes.

Electricity Safety Precautions

  • Avoid water with electricity; check cables; use fuses.

Electrical Plug Components

  • Parts of a plug: Neutral terminal, Earth terminal, Fuse, Live terminal.

Functionality of Plug Wires

  • Neutral: completes circuit. Live: high voltage. Earth: safety.

Fuse Safety Function

  • Protects from faults, preventing large currents.

Power Definition

  • Power = rate of energy transfer, measured in Watts (W).

Power-Related Calculations

  • Formula: Power = Energy / Time.

Rearranging Power Equation

  • Define energy (E) in terms of power (P) and time (t).

Work Against Resistance

  • Energy transfer through circuit resistance.

Voltmeter Connections

  • Must connect in parallel to measure potential difference.

Joules as Energy Units

  • Joules (J) = standard energy unit.

Relationship Between Voltage and Charge

  • Energy (E) = Voltage (V) × Charge (Q).

The National Grid

  • Network connecting power stations to consumers.

Meeting Electricity Demand

  • Managing electricity production based on expected demand.

Energy Loss in Transmission

  • Higher current = more heat loss; strategy uses high voltages.

Energy Generation and Transmission Losses

  • Sankey diagram shows energy loss in conversion.

Static Charge Origin

  • Atoms with equal protons/electrons = no charge; imbalance creates ions.

Creating Static Charge Through Friction

  • Insulators gain/lose electrons via rubbing.

Van de Graaff Generator Usage

  • Creates static charge for scientific purposes.

Investigating Charge Forces

  • Like charges repel; oppose attracts.

Behavior of Opposite Charges

  • Attraction between oppositely charged rods.

Electric Field Representation

  • Shows positive charge paths; line density = field strength.

Spark Generation via Electric Fields

  • High potential difference ionizes air, causing a spark.