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Refrigerators remain among the greatest consumers of electrical energy in most homes, although mandated efficiency standards have decreased their energy consumption by some \(80 \%\) in the past four decades. In the course of a day, one kitchen refrigerator removes \(30 \mathrm{MJ}\) of energy from its contents, in the process consuming \(10 \mathrm{MJ}\) of electrical energy. The electricity comes from a \(40 \%\) efficient coal-fired power plant. The electrical energy a. is used to run the light bulb inside the refrigerator. b. wouldn't be necessary if the refrigerator had enough insulation. c. retains its high-quality status after the refrigerator has used it. d. ends up as waste heat rejected to the kitchen environment.

Step by step solution

01

Analyzing Statement a

According to statement a, the electrical energy is used to run the light bulb inside the refrigerator. While it is true that a refrigerator uses electrical energy to power its light bulb, this is not its primary use. A typical refrigerator uses most of its electrical energy to pump heat out, making the food cool.

02

Analyzing Statement b

Statement b proposes that the electrical energy wouldn't be necessary if the refrigerator had enough insulation. This statement is not entirely correct. Insulation would help lessen the frequency at which the refrigerator would have to use electricity to pump out heat, but it would not totally eliminate the need for electricity.

03

Analyzing Statement c

Statement c claims that the electrical energy retains its high-quality status after the refrigerator has used it. This is not correct. After the refrigerator uses the electrical energy, this energy is transformed into kinetic energy and thermal energy where its quality is unfortunately reduced.

04

Analyzing Statement d

Lastly, statement d suggests that the electrical energy ends up as waste heat rejected to the kitchen environment. This is indeed correct. The heat extracted by the refrigerator from its contents, combined with the heat generated during operation due to inefficiency, is indeed released as waste heat into the kitchen.

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