Active element refers to the element that can stimulate the amplification, oscillation, control current or energy distribution of electrical signal and even perform data calculation and processing when energy supply is obtained. Active components include a variety of transistors, integrated circuits (ics), image tubes and displays. Passive components relative to active components, refers to the excitation of the electric signal amplification, oscillation and so on, the response to the electric signal is passive obedience, and the electric signal according to the original basic characteristics through the electronic components. The most common resistors, capacitors and inductors are passive components.