Glossary
Amperes
The SI unit for measuring electrical current, defined as one Coulomb of charge passing a given point per second.
Example:
A typical household circuit breaker might trip if the current exceeds 15 Amperes, indicating too much electricity is flowing.
Circuit
A closed loop of electrical current that allows electricity to flow from a source, through components, and back to the source, enabling devices to operate.
Example:
Turning on a flashlight completes a circuit, allowing electricity to flow from the battery to the bulb, making it light up.
Closed loop
A continuous and unbroken path within an electrical circuit that ensures current can flow completely from the power source and return to it.
Example:
For your phone charger to work, the internal wiring must form a closed loop from the wall outlet to your phone's battery.
Conserved (Electric Charge)
The principle that the total electric charge within an isolated system remains constant; it cannot be created or destroyed, only transferred between objects.
Example:
When a lightning bolt strikes, the total conserved charge in the cloud-ground system remains the same, it just redistributes rapidly.
Coulombs
The SI unit for measuring electric charge, representing the charge of approximately 6.24 x 10^18 elementary charges (like electrons).
Example:
A lightning strike can transfer many Coulombs of charge from the cloud to the ground in a fraction of a second.
Electric Power
The rate at which electrical energy is used, converted, or transferred in a circuit, measured in Watts (W).
Example:
A 100-watt light bulb consumes electric power at a rate of 100 joules per second, indicating its brightness and energy usage.
Electric charge
A fundamental property of an object or system that dictates its interactions with other charged objects or systems through electromagnetic forces.
Example:
Rubbing a balloon on your hair can transfer electric charge, causing the balloon to stick to a wall due to electrostatic attraction.
Electrical Current (I)
The rate of flow of electric charge through a conductor in an electric circuit, measured in Amperes (A).
Example:
The electrical current flowing through a phone charger cable determines how quickly your device charges.
Ohm’s Law
A fundamental relationship stating that the current (I) through an ideal resistor is directly proportional to the voltage (V) across it and inversely proportional to its resistance (R), expressed as V=IR.
Example:
Using Ohm's Law, you can calculate that a 12-volt car battery connected to a 4-ohm headlight will draw 3 amperes of current.
Parallel (connection)
A type of circuit connection where components are arranged side-by-side across the same two points, providing multiple independent paths for the current to split and flow through.
Example:
Most household outlets are wired in parallel, so if you unplug your toaster, your microwave still works because it's on a separate path.
Resistance
The opposition to the flow of electrical current in a circuit, causing electrical energy to be converted into heat or other forms.
Example:
A toaster's heating element has high resistance, which causes it to glow red hot as current passes through it, toasting your bread.
Resistors
Electronic components specifically designed to introduce a precise amount of resistance into a circuit, used to control current or divide voltage.
Example:
Small resistors are used in circuit boards to protect sensitive components by limiting the current flowing to them.
Series (connection)
A type of circuit connection where components are arranged end-to-end, providing only a single path for the entire current to flow through each component sequentially.
Example:
Old Christmas lights were often wired in series; if one bulb burned out, the entire string went dark because the single current path was broken.
Voltage
The amount of electrical potential energy per unit charge between two points in a circuit, often described as the 'electrical pressure' that drives current.
Example:
A 9-volt battery provides 9 volts of potential difference, giving energy to the charges flowing through a device like a small toy car.
Voltage drop
The decrease in electrical potential energy as charge carriers move through a component in a circuit, indicating energy conversion from electrical to other forms.
Example:
As current passes through a light bulb, there's a voltage drop across it, signifying that electrical energy is being converted into light and heat.