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  • How Does a Crank Flashlight Work?

    How Does a Crank Flashlight Work?Hand crank devices such as flashlights can be a great convenience in the field, and they can turn out to be lifesavers in a storm or emergency situation.These hand-held dynamos are relatively new to the consumer market, but the technology behind them has been around for over 175 years.

    The Parts

    These flashlights come in a variety of shapes and sizes, but they all share five basic components. They all have a crank, magnet, wire coil, an energy storage device and a bulb or LED.

    The Science

    The device works by electromagnetic induction, which is a lot more simple than it sounds. Typically, when you turn the crank, it spins the magnet within the wire coil. As the surfaces pass each other repeatedly, electrons are pulled from the magnetic field, creating electricity. The electric charge passes through the wire coil to the storage device (either a battery or capacitor) which then powers the bulb.


    How effectively these flashlights generate and store energy can vary greatly depending on the quality of the tiny generator. The norm is about 30 minutes of light generated by 30 to 60 seconds of cranking.


    Due to the self-powered nature of the flashlights, there is a tendency to think they will last forever. Over time, however, the internal storage battery or capacitor can become less efficient in holding power and eventually can fail.

    Additional Functions

    These hand-held helpers can light your way plus a great deal more. An array of hand crank equipment is available that combines flashlights with AM/FM radios, weather radios, clocks and cell phone chargers.

    Article Written By Robert Leonardi

    Robert Leonardi is a freelance writer specializing in eye care and general health-related articles. He is the president and CEO of a chain of eye care centers and has more than 30 years of experience as a licensed optician and administrator in the optical industry.

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