# Difference Between Active and Passive Components in Electronics
## 🔋 Active Components
Active components are electronic devices that **can amplify signals**, **control current**, or **produce energy**. They require an external power source to function.
### Examples:
- **Transistors** – Amplify or switch electronic signals
- **Diodes** (including LEDs) – Allow current in one direction, used in rectification
- **Integrated Circuits (ICs)** – Contain multiple active and passive components
### Key Features:
- Require external power to operate
- Can **inject power** into a circuit
- Can **control the flow** of electricity
- Used for **amplification**, **signal processing**, and **switching**
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## 🔌 Passive Components
Passive components cannot amplify or generate power. They only **respond to** the electrical signals applied to them.
### Examples:
- **Resistors** – Limit current flow
- **Capacitors** – Store and release energy as an electric field
- **Inductors** – Store energy in a magnetic field
- **Transformers** – Transfer energy between circuits via magnetic fields
### Key Features:
- Do **not require** external power to operate
- **Cannot amplify** signals
- Used for **filtering**, **energy storage**, **tuning**, and **impedance matching**
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## ⚖️ Quick Analogy
- **Passive Component**: Like a **valve or container** — it regulates or stores energy.
- **Active Component**: Like a **pump** — it can **add energy** and control the system dynamically.
An **N-channel MOSFET** (Metal-Oxide-Semiconductor Field-Effect Transistor) is a type of transistor that controls current flow using an electric field — it's a three-terminal device with:
- **Gate (G)** — controls the transistor
- **Drain (D)** — where current flows **into**
- **Source (S)** — where current flows **out of**
When a positive voltage is applied to the **gate** relative to the **source**, the MOSFET turns **on**, allowing current to flow from **drain to source** (D → S).
## ⚙️ Common Uses
- Power switching in motor drivers
- Voltage regulation
- Signal modulation
- Digital logic switching
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# 🔁 Use in an H-Bridge Motor Controller
An **H-bridge** is a circuit used to control the **direction** of a DC motor. It consists of **four switches**, typically implemented with N-channel MOSFETs:
- **Q2 + Q3 ON** → motor spins in the opposite direction
- **PWM control** on low-side N-MOSFETs allows speed control
Because N-channel MOSFETs conduct easily when their **gate voltage is higher than the source**, they're ideal for **low-side switching**. High-side use may require **gate driver circuits** to boost voltage.
