Passive

/rɪˈzɪstəns/

noun … “Opposition to the flow of electric current.”

Resistance is a property of a material or component that limits the flow of current when a voltage is applied. It is a fundamental concept in electricity and circuit design, affecting power consumption, heat generation, and signal behavior in electronic systems.

Key characteristics of Resistance include:

• Unit: measured in ohms (Ω).
• Ohm’s law: R = V / I, relating voltage (V), current (I), and resistance (R).
• Dependence on material: metals, semiconductors, and insulators have differing resistance levels.
• Temperature effects: resistance often increases with temperature for conductors and decreases for some semiconductors.
• Applications: resistors control current, divide voltages, protect components, and shape signals.

Workflow example: Calculating current through a resistor:

voltage = 12    -- volts
resistor = 1000  -- ohms
current = voltage / resistor
print(current)   -- 0.012 A

Here, the resistor limits current flow according to Ohm’s law.

Conceptually, Resistance is like friction in a pipe: it resists the flow of water (charge) and determines how easily it moves through the system.

See Current, Voltage, Power, Ohm, Electricity.

/ɪnˈdʌktər/

noun … “Component that stores energy in a magnetic field.”

Inductor is a passive electronic component that resists changes in current by storing energy in a magnetic field created around a coil of wire. Inductors are widely used in filtering, energy storage, tuning circuits, and electromagnetic interference suppression. They work in tandem with capacitors and resistors to form fundamental building blocks of analog circuits.

Key characteristics of Inductor include:

• Inductance: measured in henries (H), representing the ability to store magnetic energy per unit current.
• Current response: opposes changes in current according to V = L × (dI/dt).
• Core material: air, ferrite, or iron cores influence efficiency and magnetic properties.
• Applications: filters, transformers, chokes, energy storage in switching regulators, and oscillators.
• Series and parallel behavior: determines total inductance in circuits.

Workflow example: Current change in an inductor:

inductor = Inductor(L=0.01)   -- 10 mH
di_dt = 5                     -- rate of current change in A/s
voltage = inductor.L * di_dt
print(voltage)                 -- 0.05 V

Here, the inductor generates a voltage opposing the change in current, stabilizing the circuit.

Conceptually, an Inductor is like a flywheel for electric current: it resists sudden changes and smooths out fluctuations.

See Capacitor, Resistor, Signal Processing, AC, Power Supply.

/kəˈpæsɪtər/

noun … “Component that stores and releases electrical energy.”

Capacitor is a passive electronic component that stores energy in an electric field between two conductive plates separated by a dielectric material. Capacitors are widely used in electronic circuits for energy storage, filtering, signal coupling, timing, and voltage regulation. They can respond rapidly to changes in voltage, making them essential for stabilizing power supplies and shaping signals.

Key characteristics of Capacitor include:

• Capacitance: measured in farads (F), indicates how much charge the capacitor can store.
• Voltage rating: maximum voltage the capacitor can safely handle.
• Dielectric type: determines performance characteristics (ceramic, electrolytic, film, tantalum, etc.).
• Equivalent series resistance (ESR): affects efficiency and frequency response.
• Polarity: some capacitors are polarized (electrolytic), while others are non-polarized (ceramic, film).

Common applications of Capacitor include filtering ripple in power supplies, coupling AC signals between stages of amplifiers, timing circuits in oscillators, and energy storage in camera flashes or pulse circuits.

Workflow example: Smoothing a DC voltage:

dc_input = rectifier.convert(ac_input)
capacitor.connect(dc_input)
dc_smoothed = capacitor.charge_discharge(dc_input)

Here, the capacitor charges when voltage rises and discharges when it drops, reducing fluctuations and providing a more stable DC voltage.

Conceptually, a Capacitor is like a water reservoir: it stores water when supply is high and releases it when demand increases, keeping flow steady.

See Resistor, Inductor, Power Supply, Signal Processing, AC.

/rɪˈzɪstər/

noun … “Component that limits current flow.”

Resistor is a passive electronic component that restricts the flow of electric current in a circuit, converting electrical energy into heat. Resistors are fundamental in controlling voltage, setting current levels, dividing voltages, and protecting sensitive components. They are typically made from materials with precise resistance values, such as carbon film, metal film, or wire-wound elements.

Key characteristics of Resistor include:

• Resistance value: measured in ohms (Ω), determines how much it limits current.
• Tolerance: the accuracy of the resistance value (e.g., ±1%, ±5%).
• Power rating: maximum energy it can safely dissipate without damage.
• Temperature coefficient: how resistance changes with temperature.
• Types: fixed, variable (potentiometers or rheostats), and special types like thermistors or photoresistors.

Common applications of Resistor include current limiting for LEDs, voltage dividers, signal conditioning, biasing transistors, and filtering in combination with capacitors or inductors.

Workflow example: Limiting current to an LED:

v_supply = 5         -- volts
v_led = 2             -- LED forward voltage
i_desired = 0.02      -- 20 mA
resistor_value = (v_supply - v_led) / i_desired   -- Ohm's law
led.connect(resistor_value)

Here, the resistor ensures that the LED receives the correct current to operate safely without burning out.

Conceptually, a Resistor is like a narrow section of pipe in a water system: it slows down the flow, controlling how much water passes through.

See Voltage, Current, Power, Capacitor, Transistor.