How many kilowatt-hours of energy are necessary to heat the air in the house from 9 ∘C to 27 ∘C? The heat capacity of air is 1.03 J/g∘C.

The amount of air (in grams) is required for an answer. The process is outlined below.

Explanation:

An example for 1 kg of air:

Energy = (specific heat)*(mass)*(temperature change)

Joules = (1.03J/g°C)*(1,000g)*(27°C - 9°C)

Joules = 18540J

Coversion: 1 Joule = 2.78E-07 kwh

Kwh to heat 1 kg of air from 9 to 27°C is 5.15E-03 kwh

Use the same process with the actual mass of air in the house. If you are given house dimensions, calculate the volume and multiply by the density of air to get grams air. (Remember to subtract the volume taken up by household items (e.g., beer cans).

pure substance: iron,copper

impure substance: water,charcoal

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current