What assumptions are necessary for a market to be perfectly competitive? In light of what you have learned in this chapter, why is each of these assumptions important? For a market to be perfectly competitive, A. firms must be price takers, firms must produce a homogeneous product, and firms must be able to easily enter and exit the market. B. firms must have market power, firms must produce a differentiated product, and firms must be able to easily enter and exit the market. C. only one firm can have access to a key input, the government must regulate entry of new firms, and the long-run average cost of production must be decreasing. D. only one firm can produce output, no close substitutes may exist, and firms must not be able to enter the market. E. only a few firms may produce output, firms must have market power, and firms must produce a homogenous product.

A

Firms must be price takers, firms must produce a homogeneous product, and firms must be able to easily enter and exit the market

Explanation:

A perfectly competitive market is a market in there are many sellers of a single homogeneous goods, many buyers, abundance of information about product, free entry and exit at any point and no transaction cost. None of the (selling) firms is big enough to determine the market price. A perfectly competitive market totally follows the law of demand and supply.

Total revenue for a firm in a perfectly competitive market is the function of product price and quantity (TR = P * Q).

Option A and B is applicable for a market to be perfectly competitive, A. firms must be price takers, firms must produce a homogeneous product, and firms must be able to easily enter and exit the market. B. firms must have market power, firms must produce a differentiated product, and firms must be able to easily enter and exit the market.  

Explanation:

Perfect competition refers to the situation prevailing in a market in which buyers and sellers are in abundance and well informed that all elements of monopoly are non existent and the market price of a commodity is beyond the control of individual buyers and sellers.

For firm to attain perfect competition, certain conditions must be met. Here is a few to begin with.

From the foregoing, option A and B are satisfactory assumptions for perfect competition.

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.