The part number **2W2B-R** typically refers to a **2-Watt, 2-Ohm, Carbon Film Resistor** with a specific tolerance or packaging suffix (often "R" denotes RoHS compliance or Reel packaging). Below is a detailed breakdown of the electronic specifications and characteristics of this component. --- ### 1. Technical Specifications | Parameter | Specification | Description | | :--- | :--- | :--- | | **Power Rating** | 2 Watts (2W) | The maximum power the resistor can dissipate as heat safely. | | **Resistance Value** | 2 Ohms (2B/2R) | The electrical resistance of the component. | | **Tolerance** | ±5% (Standard) | The allowable variance from the nominal resistance value. | | **Material** | Carbon Film | A resistive film deposited on a ceramic core. | | **Lead Type** | Axial | Wires come out of both ends of the cylindrical body. | | **Coating** | Flame Retardant | Usually coated in a heat-resistant lacquer or silicone. | --- ### 2. Breakdown of the Part Name The alphanumeric code follows a standard industry naming convention for resistors: * **2W**: **Wattage.** Indicates this is a high-power resistor compared to standard 1/4W or 1/8W hobbyist resistors. * **2B / 2R**: **Resistance.** The "2" is the value, and the "B" or "R" often acts as a decimal point or a multiplier for low-ohm values. In this context, it represents **2.0 Ω**. * **-R**: **Suffix.** This usually signifies **RoHS Compliance** (Lead-free) or **Reel Packaging** (for automated assembly). --- ### 3. Key Characteristics * **High Heat Dissipation:** Because it is rated for 2 Watts, it is physically larger than standard resistors to allow for better heat cooling. * **Stability:** Carbon film resistors offer better stability and lower noise than carbon composition resistors. * **Inductance:** Being a film-type resistor, it has low inductance, making it suitable for many high-frequency applications. --- ### 4. Common Applications Due to the low resistance (2Ω) and relatively high power (2W), these parts are frequently used in: 1. **Current Sensing:** Measuring the current flow in a circuit by monitoring the voltage drop across the 2-ohm resistor. 2. **LED Drivers:** Limiting current to high-power LEDs. 3. **Audio Equipment:** Used in crossover networks or as dummy loads in small amplifiers. 4. **Voltage Dividers:** In power supply circuits where high wattage is required. --- ### 5. Identification Table (Color Code) A standard 2Ω ±5% resistor will typically have the following color bands: | Band 1 (1st Digit) | Band 2 (2nd Digit) | Band 3 (Multiplier) | Band 4 (Tolerance) | | :--- | :--- | :--- | :--- | | Red (2) | Black (0) | Gold (0.1) | Gold (±5%) | *(Note: Calculation: 20 x 0.1 = 2 Ohms)* ---