Is the DC plug mold divided into positive and negative sides?

Is the DC plug mold divided into positive and negative sides?

        In junior high school physics, the 220V electricity in the home is divided into the front and the neutral line, and the front is charged. However, many of our common electrical appliances, such as mobile phone chargers, table lamps, and TVs, why not distinguish between positive and negative, just pierce into the socket at will. ? Are there any positive and negative effects of alternating current?

　　The 220V alternating current used by our family, also known as sine wave alternating current, its polarity is changed by sine, and the positive and negative poles are also changed, so there is no problem of reverse insertion. Those with two-pin plugs are generally low-power electrical appliances. Perhaps the housing is made of all-plastics. It is not prone to leakage or electric shock. The shell is metal, and the electrical appliances with higher power will use a three-pin plug (seat) to ensure the safety of the user.

　　Electrical appliances using two-pin plugs generally do not need to divide the neutral line, which requires higher use of bipolar switches, and the neutral line is blocked together. Regardless of whether a unipolar switch or a bipolar switch is used, normal operation is not affected. When you need to touch the internal operations of the appliance, such as replacing the light bulb and overhauling, you should unplug the plug to ensure safety.