Question

An electric heating coil will consume 6.0*10^2 W of power when it is connected to a 120V outlet. A greenhouse operator has 2 such coils, and she wants to construct a single heater using the two coils to keep her small greenhouse at a temperature of 50.0 C during the winter months. For how many hours must this heater (2 coils) operate per day if an average of 1.5*10^7 J of energy are required each winter day to maintain the desired temperature given that the coils are connected

a) in series
b) in parallel

Answer 1

What do you think the answer is?

Answer 2

I really am not sure... but if I recall correctly, there is something about the parallel taking less time?

Answer 3

wait i'll give the solution.

Answer 4

just show me the process step by step please

Answer 5

ok

Answer 6

A)

Answer 7

First step. Convert the 15,000,000 J to watt-hours.
Use this link if you want.: http://www.unitconversion.org/energy/joules-to-watt-hours-conversion.html

Answer 8

Next, Step 2. Calculate the wattage for both parallel and series connection. For parallel operation all is needed is to multiply the single coil power by 2 or 1200 Watts.

For the series arrangement each coils is only getting 60 volts (1/2 of the 120) and since power = (e^2)/R it would be getting 1/4 their rated power or 600/4 for each coil or a total of 300 watts.

You now have the needed info to make a determination of how many hours a day is needed for each configuration. The problem is asking for hours not what configuration. It is not an A or B thing lol.

Answer 9

You will find that the series configuration will require 4 times the hours per day than the parallel configuration does

Answer 10

How,some,ever, the cost remains the same.

Answer 11

thank you for your answer, I really appreciate it =D