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  2. Wireless device radiation and health - Wikipedia

    en.wikipedia.org/wiki/Wireless_device_radiation...

    The antennas contained in mobile phones, including smartphones, emit radiofrequency (RF) radiation ( non-ionizing "radio waves" such as microwaves ); the parts of the head or body nearest to the antenna can absorb this energy and convert it to heat. Since at least the 1990s, scientists have researched whether the now-ubiquitous radiation ...

  3. Speaker wire - Wikipedia

    en.wikipedia.org/wiki/Speaker_wire

    Speaker wire is a passive electrical component described by its electrical impedance, Z. The impedance can be broken up into three properties which determine its performance: the real part of the impedance, or the resistance, and the imaginary component of the impedance: capacitance or inductance. The ideal speaker wire has no resistance ...

  4. Crystal radio - Wikipedia

    en.wikipedia.org/wiki/Crystal_radio

    The earphone is on left. The antenna wire, right, has a clip to attach to metal objects such as a bedspring, which serve as an additional antenna to improve reception. A crystal radio receiver, also called a crystal set, is a simple radio receiver, popular in the early days of radio. It uses only the power of the received radio signal to ...

  5. Covert listening device - Wikipedia

    en.wikipedia.org/wiki/Covert_listening_device

    A covert listening device, more commonly known as a bug or a wire, is usually a combination of a miniature radio transmitter with a microphone. The use of bugs, called bugging, or wiretapping is a common technique in surveillance, espionage and police investigations. Self-contained electronic covert listening devices came into common use with ...

  6. Wireless telegraphy - Wikipedia

    en.wikipedia.org/wiki/Wireless_telegraphy

    Wireless telegraphy or radiotelegraphy is transmission of text messages by radio waves, analogous to electrical telegraphy using cables. [ 1 ][ 2 ] Before about 1910, the term wireless telegraphy was also used for other experimental technologies for transmitting telegraph signals without wires. [ 3 ][ 4 ] In radiotelegraphy, information is ...

  7. Electromagnetic interference - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_interference

    Electromagnetic interference ( EMI ), also called radio-frequency interference ( RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. [ 1] The disturbance may degrade the performance of the circuit or ...

  8. 7.1 surround sound - Wikipedia

    en.wikipedia.org/wiki/7.1_surround_sound

    7.1 surround sound is the common name for an eight-channel surround audio system commonly used in home theatre configurations. It adds two additional speakers to the more conventional six-channel ( 5.1) audio configuration. As with 5.1 surround sound, 7.1 surround sound positional audio uses the standard front left and right, center, and LFE ...

  9. AOL Mail

    mail.aol.com

    Absolutely! It's quick and easy to sign up for a free AOL account. With your AOL account you get features like AOL Mail, news, and weather for free!