Usually a rectangular plate of material, capacitors are essential to electronics because they can perform tasks that batteries can’t. Each contains a material called a dielectric which can store electrical energy and then release it in a large burst. Capacitors are much faster than batteries at charging and releasing electricity, which makes them idea for providing the pulses of power required by camera flashes and diesel engine starters. They can also endure millions of cycles of charging and discharging, compared to mere thousands of cycles for conventional rechargeable batteries.
【正确答案】：电容器通常像是一块矩形材料板，是电子器件的重要元件，因为它们能完成电池所不能完成的任务。每个电容器里面都含有一种称为电介质的材料，它可以存储电能而后释放巨大的电脉冲。其储电和放电速度比普通电池要快得多，从而使它们成为给照相机闪光灯和内燃机启动器提供脉冲电能的理想元件。它们还可以经受住数百万次的充电和放电循环，相比之下，普通的可充电电池不过区区几千次而已。
