Solar panels capture sunlight and convert it to electricity, using photovoltaic (PV) cells. Each PV cell has several components, including two layers of silicon. One of these layers is injected with phosphorus, which creates an excess of electrons in the layer compared to pure silicon. The other layer is injected with boron, which causes the layer to have fewer electrons than pure silicon. When the two different silicon layers are put together, electrons move from the phosphorus-injected layer to the boron- Injected layer. This gives the boron-injected layer a negative charge where the two layers meet, creating an electric field at the junction of the layers. As sunlight hits a PV cell, electrons in each silicon layer become excited and move around the layer. When any electron reaches the junction between the two layers, the electric field pushes the electron toward metal conductor strips on the outside of the cell, generating electricity.
A diagram of a PV cell being exposed to sunlight is shown below. Click on the labels you want to select and drag them into the boxes to show the components of the PV cell.
- A. Phosphorus-injected layer
- B. Boron-injected layer
- C. Electric field
- D. Energy
Correct Answer & Rationale
Correct Answer: A,B,C
The components of a photovoltaic (PV) cell include the phosphorus-injected layer, which serves as the n-type semiconductor, and the boron-injected layer, acting as the p-type semiconductor. Together, these layers create a junction that facilitates the movement of electrons when exposed to sunlight. The electric field between these layers is crucial for separating charge carriers, enabling electricity generation. Option D, "Energy," is not a structural component of the PV cell but rather a result of its operation. It does not represent a physical part of the cell, making it an incorrect choice.
The components of a photovoltaic (PV) cell include the phosphorus-injected layer, which serves as the n-type semiconductor, and the boron-injected layer, acting as the p-type semiconductor. Together, these layers create a junction that facilitates the movement of electrons when exposed to sunlight. The electric field between these layers is crucial for separating charge carriers, enabling electricity generation. Option D, "Energy," is not a structural component of the PV cell but rather a result of its operation. It does not represent a physical part of the cell, making it an incorrect choice.
Other Related Questions
What statement describes one or more needed changes to this experiment that would allow the experimenter to draw a valid conclusion?
- A. Salt water should have been used to make the ice cubes for the cup of salt water.
- B. The time for ice cubes to melt should have been measured in minutes.
- C. At the beginning, both cups should have contained the same mass of water at the same temperature.
- D. The energy released should have been measured, not calculated.
Correct Answer & Rationale
Correct Answer: C
Option C highlights the necessity for both cups to start with the same mass of water at the same temperature to ensure a fair comparison. This control eliminates variables that could skew results, allowing for a valid conclusion about the melting rates of ice cubes in different solutions. Option A is incorrect because using salt water to make ice cubes would not provide relevant data on how the ice behaves in fresh versus salt water. Option B is not a change that affects the experimental validity; measuring time in minutes is appropriate, but the key is ensuring conditions are equal. Option D suggests a measurement method change, but calculating energy based on temperature changes is acceptable in this context.
Option C highlights the necessity for both cups to start with the same mass of water at the same temperature to ensure a fair comparison. This control eliminates variables that could skew results, allowing for a valid conclusion about the melting rates of ice cubes in different solutions. Option A is incorrect because using salt water to make ice cubes would not provide relevant data on how the ice behaves in fresh versus salt water. Option B is not a change that affects the experimental validity; measuring time in minutes is appropriate, but the key is ensuring conditions are equal. Option D suggests a measurement method change, but calculating energy based on temperature changes is acceptable in this context.
Which statement describes a weakness of the investigation in the passage?
- A. None of the hypotheses are directly related to the ice core data.
- B. The Greenland ice sheet is far away from the site of the explosion in Russia.
- C. Several of the hypotheses rely on unproven processes or estimated values.
- D. A few micrograms of ammonia is insufficient evidence for a conclusion.
Correct Answer & Rationale
Correct Answer: C
Option C highlights a significant weakness, as relying on unproven processes or estimated values can lead to unreliable conclusions, undermining the investigation's credibility. Option A is incorrect because hypotheses can be related to data in broader contexts, even if not directly. Option B misrepresents the geographical relevance; distance alone does not invalidate the connection between the ice core data and the explosion. Option D, while suggesting a concern about evidence quantity, does not address the fundamental issue of reliance on unproven processes that can skew the investigation's outcomes.
Option C highlights a significant weakness, as relying on unproven processes or estimated values can lead to unreliable conclusions, undermining the investigation's credibility. Option A is incorrect because hypotheses can be related to data in broader contexts, even if not directly. Option B misrepresents the geographical relevance; distance alone does not invalidate the connection between the ice core data and the explosion. Option D, while suggesting a concern about evidence quantity, does not address the fundamental issue of reliance on unproven processes that can skew the investigation's outcomes.
Placing solid ammonium nitrate, NH4NO3, in a container of water causes an endothermic reaction. The result is ammonium hydroxide, NH4OH, and nitric acid, HNO3. Which diagram shows the correct equation for the reaction?
- A. NH4OH + HNO3 → NH4NO3 + H2O + energy
- B. NH4NO3 + H2O + energy → NH4OH + HNO3
- C. NH4NO3 + H2O → NH4OH + HNO3 + energy
- D. NH4OH + HNO3 + energy → NH4NO3 + H2O
Correct Answer & Rationale
Correct Answer: B
The reaction between solid ammonium nitrate and water is endothermic, meaning it absorbs energy. Thus, the equation must reflect the consumption of energy during the process. Option B correctly shows that ammonium nitrate (NH4NO3) and water react to form ammonium hydroxide (NH4OH) and nitric acid (HNO3), while requiring energy input. Option A incorrectly suggests energy is released, which contradicts the endothermic nature of the reaction. Option C implies that energy is produced, which is also incorrect. Option D similarly misrepresents the reaction by suggesting energy is released, aligning with an exothermic process rather than the observed endothermic reaction.
The reaction between solid ammonium nitrate and water is endothermic, meaning it absorbs energy. Thus, the equation must reflect the consumption of energy during the process. Option B correctly shows that ammonium nitrate (NH4NO3) and water react to form ammonium hydroxide (NH4OH) and nitric acid (HNO3), while requiring energy input. Option A incorrectly suggests energy is released, which contradicts the endothermic nature of the reaction. Option C implies that energy is produced, which is also incorrect. Option D similarly misrepresents the reaction by suggesting energy is released, aligning with an exothermic process rather than the observed endothermic reaction.
The graph shows results from a study that sought to determine average exposure to triclosan in the U.S. population. Which statement is supported by the results in the graph?
- A. Triclosan concentration does not vary significantly among different age groups.
- B. Increased levels of triclosan in urine are related to increased age.
- C. Triclosan concentration in urine is highest in the 30- to 39-year-old age group.
- D. People aged 20-29 likely use more products containing triclosan.
Correct Answer & Rationale
Correct Answer: C
The data indicates that the highest triclosan concentration in urine occurs in the 30- to 39-year-old age group, supporting option C. This finding highlights a specific peak in exposure among this demographic. Option A is incorrect as the graph likely shows variation in triclosan levels across age groups. Option B misinterprets the data; the graph does not suggest that triclosan levels increase with age. Option D assumes usage patterns without evidence from the graph, which focuses on urinary concentration rather than product usage.
The data indicates that the highest triclosan concentration in urine occurs in the 30- to 39-year-old age group, supporting option C. This finding highlights a specific peak in exposure among this demographic. Option A is incorrect as the graph likely shows variation in triclosan levels across age groups. Option B misinterprets the data; the graph does not suggest that triclosan levels increase with age. Option D assumes usage patterns without evidence from the graph, which focuses on urinary concentration rather than product usage.