Respuesta :
(a) Power of bulb is 100 W, converting this into kW.
[tex]1 W=\frac{1}{1000}kW[/tex]
Thus,
[tex]100 W =\frac{100}{1000}kW=0.1 kW[/tex]
The bulb is used for 6 hours per day for a year, in 1 year there are 365 days thus, total hours will be:
[tex]t=6\times 365=2190 h[/tex]
Electricity used will depend on power and number of hours as follows:
[tex]E=P\times t=0.1 kW\times 2190 h=219 kW.h[/tex]
The cost of electricity is $0.15 per kW.h thus, cost of electricity for 219 kW.h will be:
[tex]Cost=\$ (219\times 0.15)=\$ 32.85[/tex]
Therefore, annual cost of incandescent light bulb is [tex]\$ 32.85[/tex]
(b) Power of bulb is 25 W, converting this into kW.
[tex]1 W=\frac{1}{1000}kW[/tex]
Thus,
[tex]100 W =\frac{25}{1000}kW=0.025 kW[/tex]
The bulb is used for 6 hours per day for a year, in 1 year there are 365 days thus, total hours will be:
[tex]t=6\times 365=2190 h[/tex]
Electricity used will depend on power and number of hours as follows:
[tex]E=P\times t=0.025 kW\times 2190 h=54.75 kW.h[/tex]
The cost of electricity is $0.15 per kW.h thus, cost of electricity for 54.75 kW.h will be:
[tex]Cost=\$ (54.75\times 0.15)=\$ 8.21[/tex]
Therefore, annual cost of fluorescent bulb is [tex]\$ 8.21[/tex].
