Introduction of flashlight

Torch: also referred to as torch, is a handheld electronic lighting tool. A typical flashlight has a battery-operated bulb and focusing mirror, and has a handle-style housing for handheld use. Although a fairly simple design, it wasn’t invented until the late 19th century because it had to combine the invention of the battery with the light bulb. In the early days, it was called “flashlight” in English because the battery’s power was insufficient, which means short-lived light.

The principle of the flashlight: one pole of the light bulb of the flashlight is in contact with the positive pole of the battery, the other pole of the light bulb is connected to one end of the switch, and the other end of the switch is connected to the negative pole of the switch. When the switch button is pressed, the battery forms a series circuit with the light bulb through the switch, and the current of the battery passes through the tungsten filament of the light bulb, causing it to heat up to an incandescent state and emit light.

The distinction between good and bad flashlights:
1. flashlight battery. There are two kinds of nickel battery and lithium battery, which can be selected according to the actual situation.
2. Light bulbs. When the light bulb is off, it is difficult for the naked eye to distinguish whether it is good or bad. You can see the consistency of the light bulb when it is on.
3. Aperture. The aperture of a good led flashlight is a uniform circle, and the light spot of a poor led flashlight is divided into two colors of yellow and blue, which are unevenly distributed.
4. Brightness. A good led flashlight has high brightness and slow decay.
5. Waterproof. A good led flashlight has waterproof function and good shock resistance, that is, it is resistant to falling.