An electric knife works by using a pair of serrated blades connected to a rotary motor and driver arm. The circular motion of the rotary motor is converted into a back-and-forth action that moves a driver arm attached to a pair of serrated blades.
The knife uses electricity to power the motor, and when the knife is turned on the driver arm begins pushing one of the serrated blades forward, while pulling the other blade back. This back-and-forth motion generates the cutting action, and can have multiple settings. An electric knife is typically used to cut different food items, and has become a useful hand-held appliance.