The is a security technique associated with the use of credit cards at the time of purchase that checks additional digits printed on the back of the credit cards. a. Address Verification System b. Advanced Authorization c. Card Verification Number d. Payment Card Industry security standard

The Payment Card Industry security standard is a security technique associated with the use of credit cards at the time of purchase that checks additional digits printed on the back of the credit cards.

Explanation:

The Payment Card Industry Standard procedures is meant to optimize the security of credit, debit and cash card transactions and protect cardholders against misuse of their personal information and protect against fraud. The PCI Standard is mandated by the card brands but administered by the Payment Card Industry Security Standards Council.

It is an information security standard for organizations that handle branded credit cards from the major card schemes. The PCI Standard is mandated by the card brands but administered by the Payment Card Industry Security Standards Council.

C. Card Verification Number

Explanation:

Card verification number also known as Card Verification Value (CVV) or card verification code (CVC) is a short unique numbers located at the back of credit cards for the purpose of security against fraud. When purchase over the internet or in phone is made with credit cards, this unique security technology request for the Card Verification number.

The numbers can either be three or four digits depending on the type of credit cards. Card Verification number helps when there's a case of data breach, it serves a the signature of the owner when making a card-not-present transactions. The security technique associated with the use of card Verification number is designed such that you have to type in the numbers at every transaction for security

sound is invisible, but sometimes we can feel it. when a kettle-drum is thumped with a stick that time the tight drum skin moving up and down very quickly for some time and then it pumped sound waves into the air. loudspeakers also work in a similar manner.

components of a speaker:

electromagnet

in order to translate an electrical signal into an audible sound, an electromagnet is used in looudspeakers

  suspension

suspension is used to   center the voice coil in the gap of the magnet and it exerts a restoring force to keep it there. suspension is used to limits the maximum mechanical excursion of the diaphragm and voice coil.

voice coil

voice coil is a coil of wire which is attached to the apex of a loudspeaker cone. it provides the motive force to the cone by the reaction of a magnetic field to the current passing through it.

cone

in a   loudspeaker, a   thin, semi-rigid membrane attached to the voice coil, which moves in a magnetic gap due to which it vibrates   and produced sound. it is known as diaphragm and it can also be called a cone, though not all speaker diaphragms are cone-shaped.

surround

surround is also known as front suspension. surround is used to join the cone to the chassis. together with the suspension it controls the cone excursion, and it is also used to   determine how energy which is   travelling through the cone is absorbed, and how the speaker limits when it reaches the ends of its travel.

dustcap

dustcap is used to protect the voice coil from dust and dirt. it is a part of the cone.

how speaker work

the outer part of the cone is fastened to the outer part of the loudspeaker's circular metal rim. the inner part is fixed to   voice coil that sits just in front of a permanent magnet . when loudspeaker is hooked up to a stereo, electrical signals feed through the speaker cables into the coil. it will convert the coil into an electromagnet magnet . when electricity flows back and forth in the cables, the electromagnet either repels or attract the permanent magnet. this moves the coil back and forth, and it pull and push the loudspeaker cone. like a drum skin vibrating back and forth, the moving cone pumps sounds out into the air.in this way loudspeakers works.

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