Na certain city, electricity costs $0.18 per kw·h. what is the annual cost for electricity to power a lamp-post for 6.50 hours per day with (a) a 100.-watt incandescent light bulb (b) an energy efficient 25-watt fluorescent bulb that produces the same amount of light? assume 1 year = 365 days.

a)

Consumption of power in one day =

Consumption of power in one year =

Since, . So,

Given that =

So, for :

$ = $

Hence, the annual cost is $.

b)

Consumption of power in one day =

Consumption of power in one year =

Since, . So,

Given that =

So, for :

$ = $

Hence, the annual cost is $.

increased stability in the completion of fluorine's outer shell.