9th Standard Science - Current Electricity Revision Crash Course

Vocabulary flashcards covering core definitions, units, components, and laws from 9th Standard Science Chapter 3: Current Electricity.

Electricity

A form of energy defined as the movement of electric charges (electrons) between two points with a potential difference.

Electric Potential

The electric level at a specific point that determines the direction of the flow of electric charges between two points.

Potential Difference ($V$)

The amount of work done per total charge transferred between two points ($V = \frac{W}{Q}$), which sets electrons into motion to produce current.

Volt ($\text{V}$)

The SI unit of potential difference, equivalent to one Joule per Coulomb ($\text{J/C}$).

Free Electrons

Electrons in the outermost shells of conductor atoms that are weakly bound to the nucleus and free to move, enabling the conduction of electricity.

Electric Current ($I$)

The flow of electrons through a conductor, defined as the amount of electric charge passing through a conductor per unit time ($I = \frac{Q}{t}$).

Ampere ($\text{A}$)

The SI unit of electric current, defined as a flow of charge of one Coulomb per second ($\text{C/s}$).

Battery

An electrical source created by joining two or more electric cells together to supply potential difference.

Ammeter

A measuring device connected in an electric circuit to determine the amount of electric current flowing through it.

Voltmeter

An instrument connected across components in an electric circuit to measure the potential difference (voltage).

Conductor

A substance with very low electrical resistance that allows electric current to flow through it easily, such as copper, aluminium, or iron.

Insulator

A material possessing extremely high electrical resistance that prevents current from passing through it, such as plastic, rubber, or wood.

Ohm's Law

The physical law stating that if the physical state of a conductor remains constant, the current ($I$) flowing through it is directly proportional to the potential difference ($V$) across its ends ($V = I \times R$).

Resistance ($R$)

The opposition or hindrance to the flow of electrons caused by collisions with atoms and ions within a conductor, measured in ohms ($\Omega$).

Resistivity ($\rho$)

A characteristic property of a conductor material that depends on its resistance, length, and cross-sectional area, given by $\rho = \frac{R \times A}{L}$.

Resistors in Series

A circuit arrangement where resistors are connected end-to-end along a single path; current remains constant throughout, and the total effective resistance is $R_s = R_1 + R_2 + R_3$.

Resistors in Parallel

A circuit arrangement where multiple resistors are connected across the same two points; voltage remains constant across each branch, and the effective resistance satisfies $\frac{1}{R_p} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3}$.