Question

1. what role does thermal energy play in the generation of electrical energy from nuclear reactions?

a. thermal energy from the reactions is used to boil water into steam, which turns a turbine of a generator system.
b. thermal energy causes the nuclear reactions to take place.
c. thermal energy is used to turn the turbine of the generator system.
d. it plays no role.

1. which of the following is true of photovoltaic cells?

a. they are made of thin layers of quartz crystals.
b. they generate electrical energy when visible light strikes their surface.
c. they generate electrical energy when any type of electromagnetic radiation strikes their surface.
d. they can only be used to run small devices, like calculators.

1. complete the following flowchart to explain how electrical energy is generated by photovoltaic cells.

flowchart with a box, then a box with electromagnetic radiation carries solar energy to earth through space., then two more boxes

Explanation:

Question 21

In nuclear power generation, nuclear reactions produce thermal energy. This thermal energy is used to heat water to produce steam. The steam then drives a turbine connected to a generator, which produces electrical energy. Option B is incorrect because nuclear reactions (like fission) are not caused by thermal energy in power generation; they are initiated by other means. Option C is incorrect as thermal energy heats water to make steam to turn the turbine, not directly turn the turbine. Option D is incorrect as thermal energy is crucial in the process of converting nuclear energy to electrical energy.

Question 22

Photovoltaic (PV) cells work on the photovoltaic effect, where visible light (a part of electromagnetic radiation) striking the PV cell's surface (made of semiconductor materials like silicon, not quartz crystals as in option A) causes electrons to be excited and generate an electric current. Option C is incorrect because not all electromagnetic radiation (e.g., radio waves, gamma rays) can effectively generate electricity in PV cells; visible light is the main part of solar radiation used. Option D is incorrect as PV systems can be used for large - scale power generation (e.g., solar power plants) and not just small devices.

Question 23

To complete the flowchart for how electrical energy is generated by photovoltaic cells, we can use the following steps (assuming the flowchart has steps in the order of energy source, energy transfer, PV cell action, and electrical energy output):

1. First Step (Energy Source): The Sun produces electromagnetic radiation (solar energy).
2. Second Step (Given): Electromagnetic radiation carries solar energy to Earth through space.
3. Third Step (PV Cell Interaction): Visible light (part of the electromagnetic radiation) strikes the surface of the photovoltaic cells.
4. Fourth Step (Energy Conversion): The photovoltaic cells convert the solar energy (from the visible light) into electrical energy.

If we were to write the steps in the flowchart boxes (from top to bottom, assuming the first box is the top - most and the given step is the second box):

• Top - most box: The Sun emits electromagnetic radiation (solar energy).
• Given box: Electromagnetic radiation carries solar energy to Earth through space.
• Next box: Visible light from the electromagnetic radiation strikes the photovoltaic cells.
• Bottom box: The photovoltaic cells generate electrical energy.

Answer:

A. Thermal energy from the reactions is used to boil water into steam, which turns a turbine of a generator system.