Glossary
Amperes (A)
The SI unit of electric current, representing one coulomb of charge flowing per second.
Example:
A circuit breaker might trip if the amperes flowing through a circuit exceed its safe limit, preventing overheating.
Brightness (of a light bulb)
The perceived intensity of light emitted by a bulb, which is directly proportional to the electrical power it dissipates.
Example:
When you dim a light, you are reducing the brightness by decreasing the power supplied to the bulb.
Current (I)
The rate of flow of electric charge through a conductor. It is measured in amperes.
Example:
The amount of current flowing through a light bulb determines how many electrons pass through it per second, affecting its brightness.
Electric Power
The rate at which electrical energy is transferred, converted, or dissipated within a circuit. It quantifies how quickly work is being done by electrical means.
Example:
A microwave oven uses a high amount of electric power to quickly heat your food.
Electric potential difference (ΔV / Voltage)
The work done per unit charge to move a charge between two points in an electric field. It represents the 'push' or 'pressure' driving current.
Example:
A car battery provides a specific electric potential difference (voltage) to power the car's electrical components.
Energy (vs. Power)
The capacity to do work. In electrical circuits, it is the total amount of electrical work done or transferred over a period, distinct from power which is the *rate* of energy transfer.
Example:
While a high-power device uses energy quickly, a low-power device used for a long time might consume more total energy.
Ohm's Law
A fundamental law stating that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance between them (V=IR).
Example:
Using Ohm's Law, an electrician can calculate the resistance needed in a circuit to achieve a desired current with a given voltage.
Ohms (Ω)
The SI unit of electrical resistance, representing the resistance between two points of a conductor when a constant potential difference of 1 volt produces a current of 1 ampere.
Example:
A typical resistor in an electronic circuit might have a value of 100 Ohms, limiting the current flow.
Parallel Resistors
Resistors connected across the same two points in a circuit, so they have the same voltage across them, and the total resistance is less than the smallest individual resistance.
Example:
Household outlets are wired with parallel resistors so that each appliance receives the full voltage, and turning one off doesn't affect the others.
Power (P)
In the context of circuits, power is the product of current and electric potential difference, representing the rate of energy transfer.
Example:
When you plug in a laptop, its power rating tells you how quickly it consumes electrical energy to operate and charge.
Resistance (R)
A measure of a material's opposition to the flow of electric current. It converts electrical energy into other forms, often heat.
Example:
The heating element in a toaster has high resistance, which causes it to glow red hot as current passes through it.
Series Resistors
Resistors connected end-to-end in a circuit, so the same current flows through each, and their total resistance is the sum of individual resistances.
Example:
In a string of old Christmas lights, if one bulb (a series resistor) burns out, the entire string goes dark because the circuit is broken.
Volts (V)
The SI unit of electric potential difference, representing one joule of energy per coulomb of charge.
Example:
Standard household outlets in the US typically provide 120 Volts of electric potential difference.
Watts (W)
The SI unit of power, representing one joule of energy transferred or dissipated per second.
Example:
A 60 Watts light bulb converts 60 joules of electrical energy into light and heat every second.