Suppose that during the past year, the price of a laptop computer fell from $2,100 to $1,820. During the same time period, consumer sales increased from 429,000 to 530,000 laptops. Calculate the elasticity of demand between these two price-quantity combinations by using the following steps. After each step, complete the relevant part of the table with the appropriate answers. (Note: For decreases in price or quantity, enter values in the Change column with a minus sign.)
Original New Average Change Percentage Change
Quantity
Price
Step 1: Fill in the appropriate values for original quantity, new quantity, original price, and new price.
Step 2: Calculate the average quantity by adding the original quantity and the new quantity, and then dividing by two. Do the same for the average price.
Step 3: Calculate the change in quantity by subtracting the original quantity from the new quantity. Do the same for the change in price.
Step 4: Calculate the percentage change in quantity demanded by dividing the change in quantity by the average quantity. Do the same to calculate the percentage change in price.
Step 5: Calculate the price elasticity of demand by dividing the percentage change in quantity demanded by the percentage change in price, ignoring the negative sign.
Using the midpoint method, the elasticity of demand for laptops is about _.

Quantity of original = 429,000

Quantity of new = 530,000

Average of quantity = 429,000+530,000 / 2 = 479500

Price of original = 2,100

Price of new = 1,820

Average of price = 2,100+1,820 /2 = $1,960

Change in quantity = 530,000 - 429,000 = 101000

Change in price = $1,820 - $2,100 = -$280

Percentage Change in quantity = (530,000-429,000)/(530,000+429,000)/2 = 21.06%

Percentage Change in price = (1,820-2,100)/(1,820+2,100)/2 = 14.29%

The price elasticity of demand using Mid-point method = 21.06/14.29 = 1.47

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.