How Faraday Flashlights Work

Animation of a shake flashlight being charged^*.

Background:

In the early 1830s, a scientist named Michael Faraday discovered that by passing a magnet through a coil of wire, a small electrical current is created. The same thing happens when a person charges a shake flashlight. A magnet passes back and forth through a coil of wire and creates an electrical current that is then stored in a capacitor. When the flashlight is turned on, the capacitor supplies the stored energy to the bulb much like a battery-powered light.

Components:

Faraday flashlights seem like they should be very complicated, but they are quite simple and only have a few components. However, the quality of these components can make a difference in your satisfaction with the light. More expensive lights usually have better quality components. The basic components of a Faraday flashlight include:

Magnet: The magnet is what generates the power as it passes through the wire coil. The stronger the magnet, the more power is generated with each shake.
Coil: The size of the wire coil (i.e. the number of windings) will also determine how much power is generated on each pass of the magnet.
Capacitor: The capacitor stores the power that you generate while shaking the flashlight. The higher the quality and larger the size of the capacitor, the longer the light output.
Switch and body: The primary considerations here are the sturdiness and waterproofness of the flashlight.
Bulb: Generally this will be an LED due to their reduced power consumption and durability. Factors include the color of the light and it's brightness.

How To Use:

To use a typical Faraday flashlight, you first shake it for 30 to 60 seconds depending on the model (or up to 3 minutes if the capacitor is fully discharged). This builds up energy in the capacitor. Now turn the flashlight on and use it like a typical flashlight until its lighting power is diminished. Then simply shake it up again and repeat the process as often as needed.

^* If you do not see the animation at the top of the page, it is because some computers are set up to block certain types of images that may be advertisements. If the image is not in motion, your browser or ad blocking software is disallowing it. Either temporarily disable those features or simply imagine the silver magnet traveling back and forth through the copper-colored coil of wire charging the capacitor.