Question

A computer with a 240-watt power supply is connected to a 120 V circuit and is left on continuously for one month (31 days). How much current does it draw? What is the resistance of the computer? How much energy does the computer use if it does not enter a power save mode? If electricity costs $0.11/kW hr, how much does it cost to leave the computer on for a month?

Answer 1

Answer:A load has resistance and this is measured in ohms. Every electrical device or load has resistance. Resistance is like a restriction to the flow of electrons and electricity is dissipated as heat energy in a resistance. For a fixed voltage applied to a load, the higher the resistance, the lower the current. Going back to the water analogy, when you stand on a hose, you increase the resistance and restrict the flow. The only way to restore the flow is by getting the pump to pump harder, and force water through the restriction, i.e. the pump needs to have a higher pressure. Alternatively if you take your foot off the hose, you increase the diameter and lower the resistance and more water can be forced through. In an electrical circuit, if the voltage is increased, more current is forced through the resistance. If the resistance is lowered, more current will flow even if the voltage doesn't change. Even connecting wires in a circuit have resistance, so when high currents need to be carried by a cable, it needs to have a sufficiently large diameter and cross sectional area (CSA) to avoid overheating.

Explanation: There is adherence to the Newton laws