You own and are the only employee of a company that sells custom embroidered pet sweaters. Last year your total revenue was $120,000. Your costs for equipment, rent, and supplies were $30,000. To start this business, you invested an amount of your own capital that could pay you a $50,000 a year return. Calculate the economic cost, normal rate of return, accoynting profit and economic profit. 3) What is the relationship between average total cost and marginal cost? 4) What is the difference between accounting cost and economic cost? 5) Define the normal rate of return. If a business has steady revenues and the future looks secure, what should the normal rate of return equal? Why?

1) total revenue = $120,000

yearly costs = $30,000

opportunity costs of investment = $50,000

3) When average total cost increases, that means that the marginal cost must be greater than the average total cost. If the addition of another unit of output does not change average total cost, it means marginal cost = average total cost.

4) Accounting costs only include explicit expenses (e.g. materials, utilities, labor, etc.), while economic costs include implicit or opportunity costs. Opportunity costs are the extra costs or benefits lost from choosing one activity or investment from another alternative.

5) The normal rate of return is how much profits does a specific investment yield (in percentage). There is no absolute good or bad rate of return. For example, risky investments that yield 15% per year are considered good investments, but some secure investments that yield 5-10% can also be considered good investments that yield high rates of return. investors are risk averse, so the riskier the investment, the higher the return they will expect form it.

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.