Many passengers on the subway refuse security checks and sometimes clash with security officers. One of the reasons is that many office workers now bring their own lunch, because the company generally does not eat, cook their own delicious safety and save money, so everyone is afraid that the food will go bad when the security check. In reality, there are many people who reject security checks, and one of the reasons why we reject them is that we do not understand the principle of security check instruments and have concerns in our hearts. Today, we will tell you whether the security inspection machine is harmful, and we will recognize some commonly used and currently the most advanced security inspection equipment.

X-ray security check machine, also known as security check machine or baggage security check machine. Everyone is familiar with it, it is the main baggage security equipment in the subway and the airport. The principle is simple, is to use the ability of X-rays to penetrate matter. The density is different, the thickness is different, the composition is different, the X-ray penetration ability is also different. The X-ray machine is based on the different penetration of various substances, so as to identify the object in the luggage.

X-ray security inspection machine can not only identify the shape of the object, but also show the color, the color of various substances are not the same. Organic materials, such as paper, clothing, and various foods, usually show orange. Mixed materials and light metals, such as those containing sodium, silicon, and aluminum, are usually shown in green. Iron, copper, and silver are shown in black and blue. The brightness of the above colors depends on the density and thickness of the material.

Many people worry that the food in their bags, from the baggage security machine so passed, X-ray so swept, the food is contaminated. There is no need to worry too much about this. The X-ray emitted by the baggage screening machine, with its low power, receives a radiation dose of less than 5 microsieverts once detected, which is far lower than those used to irradiate food. Many of the foods we eat are actually irradiated, as are other countries, such as the United States Food and Drug Administration and the United States Department of Agriculture, which have approved the following foods to be irradiated for sterilization and preservation, such as packaged frozen or frozen red meat, poultry, fresh fruits and vegetables, and grains.

Many plane crashes and deaths, as well as subway bombings and so on, are the consequences of terrorists bringing dangerous goods onto transportation. Therefore, the more carefully the security personnel check each passenger, it is responsible for the life of each passenger. We should have a positive attitude to face the inspection of security personnel, for ourselves, but also for everyone.