一、理解什么是电压电压与水压的相似之处是，水压使水管中形成水流，同样电压能推动电荷作走向移动，从而使电路中形成电流．要保持水压，必须用抽水机将水抽到高处；同样要保持电路两端的电压，就需要有电源，即电源是提供电压的装置．我们常用的手电筒，必须装人电池，小灯 First, to understand what is the voltage voltage and water pressure is similar to the water pressure in the water pipe to form a flow, the same voltage can push the charge to move, so that the formation of current in the circuit. To maintain the water pressure, the pump must be used to pump water to a high place; also to maintain the voltage across the circuit, a power supply is needed, ie, the power supply is the device that provides the voltage. Our commonly used flashlights must be equipped with batteries, small lamps