What is a flashlight?

A flashlight is a portable lighting tool, typically powered by batteries or a battery pack. It features a handheld housing and a bulb, and is used to provide illumination in dark environments. A flashlight uses a battery-powered bulb and a focused reflector to produce light. Traditional flashlights used incandescent bulbs, while modern flashlights widely use LED bulbs, which provide brighter and longer-lasting illumination.

A flashlight's switch turns the bulb on and off. Traditional flashlights typically use a simple on/off switch, while modern flashlights may have an electronic or rotary switch. Flashlights come in a variety of styles, including handheld, pen-style, and compact models, suitable for different scenarios. Flashlight performance indicators include brightness (measured in lumens), illumination distance, operating time, impact resistance, and water resistance.

What types of flashlights are used?
There are two main types of flashlights: incandescent bulbs with a tungsten filament and solid-state bulbs, typically light-emitting diodes (LEDs).

Incandescent bulbs: Traditional incandescent bulbs generate light by heating a filament to a point where it produces light. This light is generated by heating the tungsten filament with an electric current, but this is inefficient, with most of the energy lost as heat. Incandescent bulbs also have a short lifespan and are susceptible to shock.

LED bulbs: LEDs (light-emitting diodes) are semiconductor devices that emit light by releasing photons through the recombination of electrons and holes. They offer higher efficiency and a longer lifespan. Compared to incandescent bulbs, LED bulbs are more energy-efficient, durable, and less prone to damage. They can last tens of thousands of hours and provide brighter, more stable light.

Due to their high efficiency, durability, and environmental friendliness, LED bulbs have become the mainstream lighting solution for modern flashlights.