## Why we need to determine the wattage of resistor based on physical appearance?

Larger resistors are able to dissipate more heat, so can be classed to handle higher wattage. A larger wattage resistor is larger in size than a smaller wattage resistor,a larger resistor has a larger surface area or cross sectional area which heat can dissipate from due to its higher power rating !

## How do you determine the size of a resistor?

We’ll use the following formula to determine the resistor value: Resistor = (Battery Voltage – LED voltage) / desired LED current. For a typical white LED that requires 10mA, powered by 12V the values are: (12-3.4)/. 010=860 ohms.

**What does resistor wattage mean?**

The Resistor Power rating is sometimes called the Resistors Wattage Rating and is defined as the amount of heat that a resistive element can dissipate for an indefinite period of time without degrading its performance.

**What size is a 2 watt resistor?**

15.0 mm

Resistors – 2 Watt, Metal Oxide, Power

Body Length | 15.0 mm |
---|---|

Overload Voltage, maximum | 700 V |

Tolerance | ±5% |

Wattage | 2 W |

Working Voltage, maximum | 350 V |

### What is the difference between 1/4 watt and 1/2 watt resistors?

Size, a half watt resistor is bigger to radiate twice the heat that the quarter watt resistor radiates. Remember resistors convert electrical power into heat. The amount of power they can dissipate without burning out. It will have considerably more physical bulk than a similarly constructed lower wattage resistor.

### What does the physical size of resistor indicate?

Every resistor has a maximum power rating which is determined by its physical size as generally, the greater its surface area the more power it can dissipate safely into the ambient air or into a heatsink.

**Can I use a higher wattage resistor?**

The higher power rating resistor can be used. If the design rating is 1 watt the higher wattage can be used. The dissipation in the resistor will take place according to the designed rating.

**Is it OK to use a lower wattage resistor?**

Wattage refers to the maximum that a resistor can dissipate. So subbing a higher wattage for lower is perfectly fine without any changes.

## What is the difference between 1/4 Watt and 1/2 watt resistors?

## Can I use 1w resistor instead of 1 4W?

Yes, but conservative designs usually derate dissipation for increased reliability.

**What is the size of a 1/2 watt resistor?**

1/4 Watt Resistor – 2.5 x 6.5 x 28: It handles 27.77 mA when connected to 9 V source. 1/2 Watt Resistor – 3.2 x 8.5 x 28: It handles 55.55 mA when connected to 9 V source. 1 Watt Resistor – 5 x 11 x 28: It handles 111.11 mA when connected to 9 V source.

**How many Ma can a 5 watt resistor handle?**

1 Watt Resistor – 5 x 11 x 28: It handles 111.11 mA when connected to 9 V source 2 Watt Resistor – 5.5 x 15 x 35: It handles 222.22 mA when connected to 9 V source 3 Watt Resistor – 6 x 17 x 35: It handles 0.4 A when connected to 9 V source 5 Watt Resistor – 7.5 x 24 x 38: It handles 0.8 A when connected to 9 V source

### What is the size of a 3W resistor?

3 Watt Resistor – 6 x 17 x 35: It handles 0.4 A when connected to 9 V source 5 Watt Resistor – 7.5 x 24 x 38: It handles 0.8 A when connected to 9 V source Resistors above 5 watts are termed as power resistors and are usually available in different construction.

### What is the power rating of a resistor?

The higher its size, the higher the watts it can handle. The chart below presents the power rating of different resistors and their sizes. Remember that actual size may vary. Resistors above 5 watts are termed as power resistors and are usually available in different construction.