Comprehensive Physics and Environmental Science Review

Flashcards covering carbon cycle, climate change, radiation, nuclear reactions, electricity, circuit properties, and Ohm's Law based on lecture notes.

What is the carbon cycle?

The carbon cycle is the movement of carbon between the atmosphere, living things, oceans, soil, and rocks.

What is the word equation for photosynthesis, and how does it affect atmospheric carbon?

Word equation: $\text{Carbon dioxide} + \text{water} \rightarrow \text{glucose} + \text{oxygen}$. It removes $\text{CO}_2$ from the atmosphere and stores carbon in plants as glucose or biomass.

What is the word equation for cellular respiration, and what is its role in the carbon cycle?

Word equation: $\text{Glucose} + \text{oxygen} \rightarrow \text{carbon dioxide} + \text{water} + \text{energy}$. It happens in plants, animals, and microorganisms, releasing $\text{CO}_2$ back into the atmosphere.

What role do decomposers play in the carbon cycle?

Decomposers break down dead organisms and waste, releasing carbon back into the soil and releasing $\text{CO}_2$ into the atmosphere through respiration.

What human activities disrupt the carbon cycle by increasing atmospheric $\text{CO}_2$?

Burning fossil fuels, deforestation, industry, transport, and cement production.

What is the word equation for the burning of fossil fuels?

$$\text{Fuel} + \text{oxygen} \rightarrow \text{CO}_2 + \text{water} + \text{energy}$$

What is the difference between the natural greenhouse effect and the enhanced greenhouse effect?

The natural greenhouse effect keeps Earth warm enough for life. The enhanced greenhouse effect occurs when human activities increase greenhouse gases, trapping more heat and causing global temperatures to rise.

What four important greenhouse gases are listed in the notes, along with their primary sources?

$\text{CO}_2$ (fossil fuels, deforestation), Methane / $\text{CH}_4$ (livestock, wetlands, fossil fuel production), Nitrous oxide / $\text{N}_2\text{O}$ (agriculture and fertilisers), and Water vapour.

What is carbon sequestration, and what are four examples of it?

Carbon sequestration is capturing and storing carbon so it does not remain in the atmosphere. Examples include planting forests, protecting existing forests, storing carbon in soils, and carbon capture and storage (CCS).

Based on the provided energy sources summary table, what are the main advantages and main issues for solar and nuclear energy?

Solar: Main advantage is renewable with low emissions; main issue is that it depends on sunlight. Nuclear: Main advantage is low greenhouse gas emissions during operation; main issue is radioactive waste and high construction costs.

What are the three subatomic particles, their charges, and their locations in an atom?

Proton: positive ($+$), found in nucleus; Neutron: no charge, found in nucleus; Electron: negative ($-$-$$), found around the nucleus.

How is the number of neutrons in an atom calculated?

$$\text{Neutrons} = \text{Mass number} - \text{Atomic number}$$

What are isotopes, and how are Carbon-12 and Carbon-14 defined by their subatomic particles?

Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. Carbon-12 has $6$ protons and $6$ neutrons; Carbon-14 has $6$ protons and $8$ neutrons.

In nuclear notation ${}_{Z}^{A}\text{X}$, what do $A$, $Z$, and $\text{X}$ represent?

$A$ represents the mass number, $Z$ represents the atomic number, and $\text{X}$ represents the element symbol.

What is the difference between radioactivity and a radioisotope?

Radioactivity is the spontaneous release of radiation from an unstable atomic nucleus. A radioisotope is an isotope with an unstable nucleus that undergoes radioactive decay.

According to the radiation summary table, what are the properties of Alpha, Beta, and Gamma radiation?

Alpha ($\alpha$): $2\text{ protons} + 2\text{ neutrons}$, low penetration, charge $+2$. Beta ($\beta$): fast electron, medium penetration, charge $-1$. Gamma ($\gamma$): electromagnetic radiation, very high penetration, charge $0$.

What materials are required to stop Alpha, Beta, and Gamma radiation?

Alpha is stopped by paper or skin; Beta is stopped by thin aluminium; Gamma is stopped by thick lead or concrete.

What changes occur to the mass number and atomic number during alpha decay?

Mass number decreases by $4$, and atomic number decreases by $2$.

What occurs during beta decay, and how are the mass number and atomic number affected?

A neutron changes into a proton and releases an electron. The mass number stays the same, while the atomic number increases by $1$.

What happens to the mass number and atomic number during gamma decay?

Both the mass number and atomic number remain unchanged.

What is half-life, and what formula is used to calculate the remaining amount of a sample?

Half-life is the time required for half of the radioactive nuclei in a sample to decay. Formula: $\text{Remaining amount} = \text{initial amount} \times \frac{1}{2}^n$, where $n = \frac{\text{total time}}{\text{half-life}}$.

Based on the provided half-life decay table, how much of a $100\text{ g}$ sample remains after $3$ half-lives?

$$12.5\text{ g}$$

What are the common uses of radioisotopes in medicine and industry?

Medicine: medical imaging, diagnosing diseases, and treating some cancers. Industry: checking thickness of materials, detecting leaks, and checking welds.

What is nuclear fission and what describes a nuclear chain reaction?

Nuclear fission is the process where a large atomic nucleus splits into smaller nuclei, releasing energy. A chain reaction occurs when neutrons released from one fission reaction cause more nuclei to split ($1 \rightarrow 2 \rightarrow 4 \rightarrow 8 \rightarrow 16 \rightarrow \frac{...}{}$).

What is the sequence of energy transformations in a nuclear power station?

$$\text{Nuclear energy} \rightarrow \text{heat} \rightarrow \text{steam} \rightarrow \text{turbine} \rightarrow \text{generator} \rightarrow \text{electrical energy}$$

What does the Law of Conservation of Energy state?

Energy cannot be created or destroyed — it can only be transferred or transformed.

What is the formula for calculating energy efficiency?

$$\text{Efficiency} = \frac{\text{Useful energy output}}{\text{Total energy input}} \times 100$$

What do the different arrows represent in a Sankey diagram?

The arrow going in represents input energy, the useful arrow represents useful energy, and smaller branching arrows represent wasted or unwanted energy. The width of each arrow represents the amount of energy.

What are the definitions, symbols, and units for electric current, voltage, and resistance?

Current ($I$, unit: ampere / $\text{A}$) is the rate of flow of electric charge. Voltage ($V$, unit: volt / $\text{V}$) is the energy transferred per unit of charge. Resistance ($R$, unit: ohm / $\Omega$) is the opposition to the flow of electric current.

What are the three mathematical expressions of Ohm's Law?

$V = I R$, $I = \frac{V}{R}$, and $R = \frac{V}{I}$

According to the comparison table, how do series and parallel circuits compare regarding pathways, current, voltage, and component failure?

Series circuits have one pathway, same current everywhere, shared voltage, and if one breaks all stop. Parallel circuits have multiple pathways, split current, same voltage across branches, and if one breaks others can still work.

What is an electromagnet, and how can its strength be increased?

An electromagnet is a coil of wire carrying electric current that creates a magnetic field. Adding an iron core makes the electromagnet stronger.

What is electromagnetic induction, and how is it used in a generator?

Electromagnetic induction is the process where moving a conductor through a magnetic field produces an electric current. A generator uses this process to convert mechanical energy into electrical energy ($\text{Movement} \rightarrow \text{magnetic field interaction} \rightarrow \text{induced current} \rightarrow \text{electricity}$).