Understanding Electricity: Concepts and Calculations

Electrostatics

Study of electric charges at rest.

Proton

Positively charged particle in an atom.

Electron

Negatively charged particle in an atom.

Neutron

Neutral particle in an atom.

Static Electricity

Charge imbalance on objects due to electron transfer.

Insulator

Material that does not allow charge flow.

Conductor

Material that allows charge flow easily.

Electric Field

Region around charged object affecting other charges.

Field Lines

Visual representation of electric field strength and direction.

Current

Movement of electrons through a conductor.

Conventional Current

Flow of current from positive to negative.

Electric Current

Actual flow of electrons from negative to positive.

Power Source

Device providing energy to drive current.

Circuit Diagram

Visual representation of electrical components and connections.

Charge (C)

Measured in Coulombs, represents electric charge.

Current (A)

Measured in Amperes, rate of charge flow.

Time (s)

Measured in seconds, duration of current flow.

Milliamps (mA)

Unit for small currents, 1 A = 1000 mA.

Ammeter

Device used to measure electric current.

Potential Difference (P.D.)

Force pushing electrons through a circuit.

Volts (V)

Unit of potential difference or voltage.

Voltmeter

Device used to measure potential difference.

Energy Transferred

Work done by charges in a circuit component.

Charge Flow Calculation

Charge = current x time formula.

Electric Field Speed

Electric field created close to speed of light.

Charge Flow Example

1.68 C charge from 14 mA over 120 s.

Electrical Working

Energy transferred equals potential difference times charge.

Potential Difference (P.D.)

Voltage across components in a circuit.

Series Circuit

Single loop with identical current throughout.

Ammeter

Device used to measure current in a circuit.

Voltmeter

Measures potential difference across circuit components.

Parallel Circuit

Multiple loops allowing independent current flow.

Current Conservation

Currents in parallel add to total current.

Resistance

Opposition to current flow, measured in Ohms (Ω).

Ohm's Law

Current is directly proportional to voltage at constant temperature.

Resistance Calculation

Resistance equals potential difference divided by current.

Variable Resistor

Allows user to adjust resistance in a circuit.

Characteristic Graph

Plots current against potential difference for components.

Linear Circuit Element

Resistance remains constant with varying potential difference.

Non-linear Circuit Element

Resistance changes with varying potential difference.

Diode

Component allowing current flow in one direction only.

LED

Light Emitting Diode; emits light when current flows.

Mains Voltage

Standard voltage supplied to homes, typically 230V.

Alternating Voltage Frequency

Mains electricity operates at 50Hz frequency.

Current (I) Symbol

Represents electric current in equations.

Resistance Change Factors

Resistance varies with temperature and material properties.

Current Measurement

Measured in Amperes (A) using an ammeter.

Voltage Measurement

Measured in Volts (V) using a voltmeter.

Power Transmission

Electricity delivered to homes via national grid.

Electrical Energy Formula

Energy (J) equals voltage (V) times charge (C).

Resistor Function

Limits current flow in electrical circuits.

Temperature Effect on Resistance

Higher temperatures increase resistance in conductors.

Circuit Loop Independence

In parallel circuits, loops operate independently.

Live Wire

Brown wire that carries current to appliance.

Neutral Wire

Blue wire that completes the circuit.

Ground Wire

Green and yellow wire for safety connection.

Complete Circuit

Path for current to flow through appliance.

Safety Feature

Prevents electric shock and equipment damage.

Double Insulation

No Earth pin needed for safety.

Net Resistance

Total resistance across all circuit components.

Series Circuit

Current is equal throughout the circuit.

Parallel Circuit

Potential difference is equal across each loop.

Potential Difference (P.D)

Energy transferred per unit charge.

Ohm's Law

V = I x R, relates voltage, current, resistance.

Power (P)

Energy transferred per second, measured in watts.

Kilowatt (kW)

Unit of power equal to 1000 watts.

Megawatt (MW)

Unit of power equal to 1,000,000 watts.

Power Formula

P = V x I, relates power, voltage, current.

Resistance and Temperature

Higher temperature increases resistance in wires.

Resistance vs Length

Longer wires have higher resistance.

Resistance vs Area

Thicker wires have lower resistance.

Charge (Q)

Q = I x t, relates charge, current, time.

Energy (E)

E = Q x V, relates energy, charge, voltage.

Resistors in Series

Total resistance is R1 + R2.

Resistors in Parallel

Total resistance is half for equal resistors.

Current at Junction

Total current in equals total current out.

Current Definition

Rate of flow of electric charge.

Voltage Definition

Energy transferred per unit of charge.

Current Squared Formula

P = I² x R, relates power, current, resistance.

V = I x R

Formula for calculating potential difference.