Answer:
3.5 Wh
$11.72
Explanation:
The electrical energy consumed is equal to the power times the time (E = Pt). Power is equal to the voltage times the current (P = VI), where one Watt equals Volt times Ampere (1 W = VA). Given the voltage and the current, we can calculate the power consumed by the bulb. We can then calculate the energy consumed for a given amount of time, and the cost of that energy.
First, find the power consumed by the bulb.
Power = voltage × current
Power = (50 V) (0.21 A)
Power = 10.5 W
Now calculate the energy consumed in 20 minutes.
Energy = power × time
Energy = (10.5 W) (20 min) (1 hr / 60 min)
Energy = 3.5 Wh
Finally, calculate the cost of the energy consumed in 90 minutes daily for two months.
Cost = energy × price
Cost = (power × time) × price
Cost = (3.5 Wh) (90 min/day) (30 day/month) (2 month) (0.62 $/kWh) (1 kW / 1000 W)
Cost = $11.718
