Question

Compare the energy consumption of two commonly used items in the household. calculate the energy used by a 1.20 kw toaster oven, wtoaster, which is used for 6.20 minutes and then calculate the amount of energy an 11.0 w compact fluorescent light (cfl), wlight, bulb uses when left on for 8.50 hours.

Answer 1

Toaster oven:

Power: $P=1.20 kW$

Time: $t=6.20 min \cdot \frac{1}{60 min/h}=0.103 h$

So, the energy consumed by the oven is

$E=Pt=(1.20 kW)(0.103 h)=0.124 kWh$

Fluorescent light:

Power: $P=11.0 W=0.011 kW$

Time: $t=8.50 h$

So, the energy consumed by the light is

$E=Pt=(0.011 kW)(8.50 h)=0.094 kWh$

So, the toaster oven has consumed more energy than the fluorescent light.

Answer 2

we know energy = power*time(in hour) so energy used by 1.20kw(1200 watt) toast oven used for 6.2 min(6.2/60 hour) = 1200*(6.2/60)=1200*0.103 = 124 watt hour. Energy used by 11 w cfl used for 8.50 hour = (11*8) + (11* (50/60)) = 88+9.166=97.166 watt hour.