Journalize these accounting transactions. (credit account titles are automatically indented when the amount is entered. do not indent manually.) (a) stockholders invested $12,000 in the business in exchange for common stock. (b) insurance of $800 is paid for the year. (c) supplies of $1,800 are purchased on account. (d) cash of $7,500 is received for services rendered

a. Accounts and explanation         debit              credit

   cash                                             $12,000      

   common stock                                                   $12,000

b.  Accounts and explanation         debit              credit

    insurance expenses                    $800

    cash                                                                    $800

c. Accounts and explanation         debit              credit

   supplies                                       $1,800

   accounts payable                                              $1,800

d.  Accounts and explanation         debit              credit

    cash                                              $7,500

    service revenue                                                 $7,500

Explanation:

a. stock is issued for cash

b. paid 1 year insurance policy

c. purchased supplies on account

d. received cash for service rendered

water and oil do not mix because water is hydrophilic (it is attracted to itself) and oil is hydrophobic (it is repelled by water).

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.