Seepage
The slow movement of a fluid (typically water) through a porous material, such as soil or the pores in a rock
Ionising radiation
- Radiation carrying enough energy to liberate electrons from atoms or molecules, thereby ionizing them
- Examples include alpha particles, beta particles, gamma rays, and X-rays
Name four types of social causes that society has on the environment
- Population Growth: Increased demand for resources like water, food, and land
- Overconsumption: High rates of consumption, particularly in developed nations, leading to resource depletion and increased waste
- Industrialization & Pollution: Release of pollutants from industries, energy production, and manufacturing into the air, water, and soil
- Deforestation: Clearing forests for agriculture, urban development, or timber, leading to habitat loss, soil erosion, and increased atmospheric CO₂
Describe two things energy added to a system can do
- Increase the internal energy of the system (raising its temperature)
- Allow the system to do work on its surroundings (e.g., by expanding)
Environmental effects of acid rain
- Acidification of lakes and rivers, killing fish and other aquatic life
- Damage to forests and soils, by leaching essential nutrients and releasing aluminum
Exergy means…
The quality of energy
Cogeneration plants are…
Power plants that generate electricity but also sell and /or utilize waste heat for industrial processes
A solar heater is usually covered with one or more glass plates… because
The optical properties of these covers give rise to the “greenhouse effect”
- Reasoning: Glass is transparent to incoming short-wave solar radiation but is opaque to the longer-wavelength infrared radiation re-emitted by the heated absorber plate. This traps the heat inside the collector.
Energy gap of a semiconductor refers to…
the energy difference between the top of the valence band and the bottom of the conduction band
What are the layers in solar cells
- p-type semiconductor layer
- n-type semiconductor layer
- The p-n junction
- Front Contact
- Anti-reflection Coating
- Back Contact
Explain the p-type semiconductor layer
This layer is doped with atoms that create a surplus of positive charge carriers called “holes.”
Explain the n-type semiconductor layer
This layer is doped with atoms that create a surplus of negative charge carriers (electrons)
Explain the The p-n junction
- At the interface where the p-type and n-type materials meet, electrons from the n-side diffuse into the p-side, and holes from the p-side diffuse into the n-side
- This creates a region called the depletion zone with a built-in electric field that prevents further diffusion
Explain the Front Contat
A grid of metal fingers that collects the generated electrical current without blocking too much sunlight
Explain the Anti-reflection Coating
A thin layer applied to the top surface to minimize the reflection of light, allowing more photons to enter the semiconductor material
Explain the Back Contact
A solid metal layer that covers the entire back surface, completing the electrical circuit
