Electricity Lecture Notes

Comprehensive vocabulary flashcards covering the fundamental concepts of electricity, including charge, potential difference, Ohm's law, power, energy, and the heating effect of current based on the lecture notes.

Charge ($Q$)

A physical property of matter that can be positive or negative; like charges repel ($+ \text{ and } +$, $- \text{ and } -$) and unlike charges attract ($+ \text{ and } -$).

Coulomb ($c$)

The SI unit of electric charge.

Fundamental charge ($e^-$)

The smallest independent charge, where $1e^- = -1.6 \times 10^{-19}$ Coulomb.

Electric Current ($I$)

The rate of flow of positive charge through a conductor, calculated using the formula $I = \frac{Q}{t}$ ($\text{Charge} / \text{Time}$).

Ampere ($A$)

The SI unit of electric current; defined as one coulomb of charge flowing through a conductor in one second ($1A = 1C / 1s$).

Potential Difference ($V$)

The amount of work done in moving a unit charge ($1C$) from one point to another, expressed as $V = \frac{W}{Q}$.

Volt ($V$)

The SI unit of potential difference, where $1 \text{ Volt}$ is achieved if $1 \text{ Joule}$ of work is done moving a charge of $1 \text{ Coulomb}$.

Voltmeter

An instrument used to measure the potential difference between two points in an electric circuit.

Ammeter

An instrument used to measure the electric current flowing through a circuit.

Resistance ($R$)

The property of a conductor to oppose the flow of electric current; its factors include length ($l$), cross-sectional area ($A$), material, and temperature.

Resistivity ($\rho$)

A property of the material that does not change with shape or size (length or area); its SI unit is the ohm-meter ($\text{ohm m}$).

Ohm's Law

The principle stating that the potential difference $V$ across a metallic conductor is directly proportional to the current $I$ flowing through it, provided temperature remains the same; $V = IR$.

Series Combination

A circuit arrangement where resistors are connected in sequence, resulting in the same current throughout but different voltage across each component; $R_e = R_1 + R_2 + R_3$.

Parallel Combination

A circuit arrangement where resistors are connected across the same points, resulting in the same voltage across each but different currents; $\frac{1}{R_e} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3}$.

Electric Power ($P$)

The rate at which electric energy is consumed, measured in Watts ($W$); formulas include $P = VI$, $P = I^2R$, and $P = \frac{V^2}{R}$.

Electrical Energy ($E$)

The energy supplied by a cell or source over time, calculated as $E = P \times t$ with the SI unit being Joules ($J$).

Kilowatt-hour ($kWh$)

The commercial unit of electrical energy, where $1 \text{ unit} = 1 \text{ kWh} = 3.6 \times 10^6 \text{ Joules}$.

Joule's Law of Heating

States that the heat ($H$) produced in a resistor is directly proportional to the square of the current ($I^2$), the resistance ($R$), and the time ($t$) for which the current flows ($H = I^2Rt$).

Electric Fuse

A safety device based on the heating effect of current, used to prevent short circuits; it is made of an alloy with high resistivity and a low melting point.

Tungsten

The material used for filaments in electric bulbs because it has a very high melting point and emits light when heated.

Electric cell (Dry cell)

A device that maintains a potential difference across a conductor, causing current to flow from higher potential to lower potential.

Electric Circuit

A continuous and closed path through which electric current can flow.

Variable Resistance or Rheostat

A component in a circuit used to change the resistance, and thus regulate the current, without changing the voltage source.