It costs $336.384 to run a given giant screen TV all the time for 365 days. By choosing to use your TV's power-saving feature, the average current drawn drops to 0.275 Amps on the same 120 Volt circuit. How much do you save per year by using this feature (cost per kWh is $0.20) versus leaving it on all the time?

The amount saved in a year is $ 278.6.

Explanation:

current, I = 0.275 A

Voltage, V = 120 V

cost = $ 0.20 per kWh

The energy spent in 1 year is given by

E = V I t

E = 120 x 0.275 x 365 x 24 x 3600

E = 1.04 x 10^9 J

1 kWh = 3.6 x 10^6 J

So,

E = 288.9 kWh

So, the cost is

C = $ 0.2 x 288.9 = $ 57.78

So, the amount saved = $ 336.384 - $ 57.78 = $ 278.6  

3.2x10^7

causes

fossil fuels burn

cities become more industrialized

human population grows worldwide