Question
c. A solar cell that transforms 300 J of light energy into 45 J of electrical energy and 255 J of heat and sound energy.
Answer
4.1
(269 Votes)
Yana
Elite · Tutor for 8 years
Answer
The efficiency of a device converting energy can be computed using the formula η = (Eout / Ein) * 100% , where η stands for the efficiency, Eout for the output energy and Ein for the input energy. In this case our input energy (Ein) is the total light energy observed by the solar cell, which is 300 J, and our output energy (Eout) is the electrical energy produced by it, which is 45 J. By inserting these numbers into the formula we get η = (45 J / 300 J) * 100% = 15%, implying the solar cell's efficiency at converting light energy into electric energy is 15% .
Explanation
The question falls within the realm of energy conversions. It describes a solar cell's transformation process, where 300 Joules (J) of light energy is converted into electrical and thermal (heat + sound) energy. The law of conservation of energy states that energy can change forms but cannot be created or destroyed. The question mentions an energy transformation from light energy into electrical energy and other forms of energy such as heat and sound. The efficiency of an energy conversion process refers to the ratio of the useful output energy (or power) to the input energy (or power), often expressed as a percentage. Here our input energy is 300 J of light energy and our useful output is 45 J of electrical energy. We are therefore essentially asked to calculate the efficiency of the solar cell using these two values.