A student in a town in India, where the price per unit (1 unit = 1 kWh ) of electricity is ₹   5 . 00 , purchases a 1 kVA UPS (uninterrupted power supply) battery. A day before the exam, 10 friends arrive to the student's home with their laptops and all connect their laptops to the UPS. Assume that each laptop has a constant power requirement of 90   W . Consider the following statements. I. All t

Step-by-step solution

Power requirement for 1 laptop, P 1 = 90   W So, power r quirement for 10 laptops, P = 10 × P 1 = 10 × 90 - 900   W = 0 . 9   kW In 5   h , electrical energy used by all laptops, E = P × t = 0 . 9 × 5 = 4 . 5 kWh cost of electrical energy used is cost = E × Unit cost = 4 . 5 × 5 = ₹   22 . 50 So, statement III is correct. For laptop charger, input voltage is 220   V So, current when all 10 laptops are connected through an extension, I = P V = 900 220