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A battery indicator (also known as a battery gauge) is a device which gives information about a battery. This will usually be a visual indication of the battery's state of charge . It is particularly important in the case of a battery electric vehicle .
For higher voltages, a statiscope consisting of a neon glow tube mounted on a long insulating handle can be used to detect AC voltages of 2000 volts or more. For low voltage work (for example, in automobiles), the lamp used is usually a small, low-voltage incandescent light bulb. These lamps usually are designed to operate on approximately 12 V ...
Others use incandescent bulbs mounted in reflectors. LED penlights are becoming increasingly common. Low-cost units may be disposable with no provision to replace batteries or bulbs and are sometimes imprinted with advertising for promotional purposes. A headlamp is designed to be worn on the head, often having separate lamp and battery ...
An electric battery is a source of electric power consisting of one or more electrochemical cells with external connections [1] for powering electrical devices. When a battery is supplying power, its positive terminal is the cathode and its negative terminal is the anode. [2] The terminal marked negative is the source of electrons.
Lithium batteries produce a higher voltage (3.2–3.7 V nominal), and are thus not a drop-in replacement for AA (alkaline or NiMh) batteries without circuitry to reduce voltage. Although a single lithium cell will typically provide ideal power to replace 3 NiMH cells, the form factor means that the device still needs modification.
The violet glow of a blacklight is not the UV light itself, but visible light that escapes being filtered out by the filter material in the glass envelope. A blacklight , also called a UV-A light , Wood's lamp , or ultraviolet light , is a lamp that emits long-wave ( UV-A ) ultraviolet light and very little visible light .
Lightbulb jokes are often responses to contemporary events. [14] For example, the lightbulb may not need to be changed at all due to ongoing power outages. [15]The Village Voice held a $200 lightbulb joke contest around the time of the Iran hostage crisis, with the winning joke being: [16]