If you used 400 W of power for 30 h, you have used
Answer: Option D
Explanation:
The power is multiplied by time then the energy is: E = P*T. E = 400*30 = 12*10^3. = 12KWH.
At the end of a 14 day period, your utility bill shows that you have used 18 kWh. What is your average daily power?
Answer: Option A
18 kwh for 14 days. For one day power consumption is = 18/14. = 1.2857
A 15 V source is connected across a 12 Ω resistor. How much energy is used in three minutes?
Answer: Option B
As per ohm's law, R = V / I I = V / R = 15 / 12 = 1.25 A And Power P = V * I = 15*1.25 = 18.75 w Given duration is 3 miniute i.e. 3 / 60 hour Therefore, Watt-hour = 18.75 * (3 / 60) = 0.9375
A given power supply is capable of providing 6 A for 3.5 h. Its ampere-hour rating is
Answer: Option C
The capacity of battery generally expressed in AH, so that in this case AH is 6A*3.5H=21AH
A power supply produces a 0.6 W output with an input of 0.7 W. Its percentage of efficiency is
Efficiency=output/input =. 6\.7 =. 857 % efficiency =. 857*100 = 85.7%
