Assume you are going to lunch and have a choice of two meals. the first meal would give an increase in marginal utility of 100 with a $25 price. the second meal would give you an increase of only 10 with a $2 price. the third meal will give you an increase of 50 with a $5 price. which meal should you logically choose ?
a. first
b. second
c. third
d. none of the above

C) Third

Explanation:

The first meal gives you 4 units of utility for every dollar spent (= 100 utility / $25).

The second meal gives you 5 units of utility for every dollar spent (= 10 utility / $2).

The third meal gives you 10 units of utility for every dollar spent (= 50 / $5). We should choose the meal that provides us with the greatest utility per dollar.

Third meal

Explanation:

Marginal utility is the satisfaction gotten from consuming an extra product(in this case an extra meal at a restaurant).

Based on logic the meal to be chosen is the third because it gives a reasonably high marginal utility for a very affordable price range. The first meal although it gives the highest utility would be very price demanding, which would not be desirable.

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.