Hoja de repaso: Fundamentals of Physics and Earth Systems

📋 Course Outline

1. Wave behavior and sound
2. Light interactions and color
3. Electromagnetic radiation
4. Energy transfers and power
5. Magnetism and electrostatic forces
6. Electric circuits and resistance
7. Electromagnets and motors
8. Water cycle and Earth systems
9. Photosynthesis and carbon cycle
10. Bionic eye technology

📖 1. Wave behavior and sound

🔑 Key Concepts & Definitions

• Pitch : Pitch is the perceived highness or lowness of a sound determined by the wave’s frequency and wavelength.
• Wavelength : Wavelength is the distance between repeating points on a wave, measured along the direction of travel.

📝 Essential Points

• For sound waves, a shorter wavelength corresponds to a higher pitch.
• For sound waves, a longer wavelength corresponds to a lower pitch.
• Sound pitch is linked to how frequently the wave cycles occur, so frequency and wavelength act together for this relationship.

💡 Memory Hook

Shorter wavelength → higher pitch; longer wavelength → lower pitch.

📖 2. Light interactions and color

🔑 Key Concepts & Definitions

• Amplitude : Amplitude is the maximum displacement of a wave from its equilibrium position.
• Refraction : Refraction is the change in direction of light when it passes between materials.

📝 Essential Points

• Light’s brightness is associated with amplitude (bigger amplitude means brighter light).
• Prisms separate white light because different wavelengths refract by different amounts.
• For the refraction scenario, the refraction is taking place at the spoon-water boundary where light changes medium.

💡 Memory Hook

Prism splits by wavelength; amplitude sets brightness.

📖 3. Electromagnetic radiation

🔑 Key Concepts & Definitions

• Electromagnetic spectrum : The electromagnetic spectrum is the range of electromagnetic radiation types ordered by wavelength and frequency.
• Radio waves : Radio waves are electromagnetic radiation with the longest wavelengths in the spectrum.

📝 Essential Points

• Radio waves have the longest wavelengths among the listed electromagnetic radiation types.
• Electromagnetic radiation can travel through space.
• Electromagnetic radiation does not require particles traveling through a medium to transmit energy or information.
• Electromagnetic radiation has a wavelength and can be used to transmit information.

💡 Memory Hook

Longest wavelengths in the spectrum → radio waves.

📖 4. Energy transfers and power

🔑 Key Concepts & Definitions

• Gravitational potential energy : Gravitational potential energy is energy stored due to an object’s height or position in a gravitational field.
• Kinetic energy : Kinetic energy is energy of motion, given by $E_k=\tfrac12mv^2$.

📝 Essential Points

• Kinetic energy increases with both mass and the square of speed, so reaching a higher top speed raises $E_k$.
• For $E_k=\tfrac12mv^2$, the correct option for the pole vaulter’s kinetic energy at top speed is 18,000 J.
• For gravitational potential energy $E_p=mgh$, the correct option for the pole vaulter at maximum height is 17,640 J.
• In the hydroelectric unit, gravitational potential energy of water spins turbines to generate electrical energy for running the plant.

💡 Memory Hook

Dam: height (gravitational) → motion (kinetic) → electricity.

📖 5. Magnetism and electrostatic forces

🔑 Key Concepts & Definitions

• Magnetic attraction : Magnetic attraction is the force that pulls a magnetic material toward a magnet.
• Electrostatic force : Electrostatic force is the attraction or repulsion between objects due to electric charge.

📝 Essential Points

• A testable question is one that changes a measurable factor and observes a measurable outcome, such as how magnet count affects nails picked up.
• Increasing the strength of a magnet increases the magnetic attraction.
• Decreasing the distance between the magnet and the object increases the magnetic attraction.
• The non-contact force most appropriate for pulling a non-magnetic aluminium car using a rubbed PVC pipe and wool is the electrostatic force.
• Rubbing the PVC pipe more increases the negative charge on the pipe due to a build-up of electrons.

💡 Memory Hook

More rubbing → more charge difference → stronger electrostatic pull.

📖 6. Electric circuits and resistance

🔑 Key Concepts & Definitions

• Resistance : Resistance is how strongly a component opposes current flow in a circuit.
• Ohm's law : Ohm’s law links voltage, current, and resistance using $V=IR$.

📝 Essential Points

• Resistor symbols in circuit diagrams are unfilled rectangles.
• To make a bulb brighter, decrease resistance and increase voltage.
• For a 12 V battery, with a 5 $\Omega$ resistor added to a bulb of 1 $\Omega$, the current in the series circuit is 2 A.
• In the series circuit with identical components, the current limit at Point A is set by the total circuit resistance of the branches.

💡 Memory Hook

Series brightness favors lower $R$; use $V=IR$ to find current.

📖 7. Electromagnets and motors

🔑 Key Concepts & Definitions

• Electromagnet : An electromagnet is a temporary magnet produced when current flows through a coil.
• Electric motor : An electric motor converts electrical energy into rotational motion using electromagnetic interactions.

📝 Essential Points

• A suitable testable question for electromagnet strength is how iron-nail width affects the number of staples picked up.
• The most appropriate conclusion from the results table is that as the width of the iron nail increases, the strength of the electromagnet increases.
• The magnetic field is strongest at the ends of the nail, matching the observation that the ends pick up more staples.
• A magnet is needed in the motor because the magnetic field from the magnet interacts with the magnetic field from the coil, causing the coil to spin.

💡 Memory Hook

Electromagnet strength ↑ with nail width (in the table); motor works by magnet-field interaction to rotate.

📖 8. Water cycle and Earth systems

🔑 Key Concepts & Definitions

• Water cycle : The water cycle is the continuous movement of water through evaporation, condensation, precipitation, and runoff.
• Earth systems : Earth systems are interacting parts of the planet such as the atmosphere, hydrosphere, geosphere, and biosphere.

📝 Essential Points

• The correct water-cycle sequence is evaporation, condensation, precipitation, runoff.
• Fresh water is limited in many places because precipitation does not fall evenly over the Earth’s surface.
• In the listed categories, a flowing lava example belongs to the geosphere, and a lifeless polluted river belongs to the hydrosphere.
• A tiger is part of the biosphere, while the Greenland ice sheet is part of the geosphere.
• Winds are movements of air in the atmosphere and can also carry other types of matter.

💡 Memory Hook

E-C-P-R: Evaporation → Condensation → Precipitation → Runoff.

📖 9. Photosynthesis and carbon cycle

🔑 Key Concepts & Definitions

• Photosynthesis : Photosynthesis is the chemical reaction in which light energy is used to form glucose and oxygen from carbon dioxide and water.
• Respiration : Respiration is the process by which living cells release energy by breaking down glucose, typically using oxygen.

📝 Essential Points

• In photosynthesis, light energy from the Sun is converted into chemical energy stored in glucose.
• Respiration provides energy by releasing the chemical energy of glucose.
• In respiration, oxygen is required and carbon dioxide is produced, which makes respiration the opposite direction of photosynthesis for these gases.
• The best explanation for oxygen being about 21% in Earth’s atmosphere is that photosynthesizing organisms produce oxygen as a product of chemical reactions.
• Fuel + oxygen → carbon dioxide + water + energy is the general combustion form represented in the choices.
• Carbon cycles between atmosphere and oceans via gas exchange.

💡 Memory Hook

Photosynthesis: CO2 + H2O + light → glucose + O2; Respiration: glucose + O2 → CO2 + H2O + energy.

📖 10. Bionic eye technology

🔑 Key Concepts & Definitions

• Prosthetic : A prosthetic is an artificial body part or implant that replaces or supports a natural body part.
• Bionic : Bionic describes an artificial body part that is typically electromechanical and substitutes for or enhances natural biological capability.
• Nanowire : A nanowire is a tiny wire with a diameter around $10^{-9}$ m.
• Electrochemical Eye (EC-Eye) : The Electrochemical Eye is a 3D artificial eye concept using an electrochemical process and a 3D artificial retina.

📝 Essential Points

• The new 3D artificial eye was developed by Hong Kong University of Science and Technology (HKUST).
• A stated advantage is that it may offer sharper vision than a human eye in the future.
• Two limitations mentioned for existing prosthetic eyes are poor resolution from 2D flat image sensors and reliance on external spectacles with cables.
• The article states that scientists collaborated with the University of California, Berkeley and will need further medical research experts.

💡 Memory Hook

EC-Eye: 3D nanowire retina + electrochemical process → better resolution and possible night vision.

⚠️ Common Pitfalls & Confusions

1. Confusing pitch with brightness: pitch depends on frequency/wavelength, while brightness is linked to light-wave amplitude.
2. Thinking sound can travel in empty space: sound requires a medium to transmit vibrations.
3. Mixing up refraction and reflection: the spoon appears different because light refracts at the spoon-water boundary, not because it reflects off the spoon.
4. Assuming more magnet mass increases attraction: the factor emphasised here is distance, magnet strength, and charge effects for the non-magnetic challenge.
5. Using Ohm’s law incorrectly by treating parallel and series the same: the current options in the calculation depend on the total resistance in the circuit used.
6. Reaching the motor explanation by electricity alone: the motor spins because magnetic fields interact between the magnet and the coil.
7. Mistaking the water-cycle order: evaporation happens first, then condensation, then precipitation, then runoff.

✅ Exam Checklist

1. Relate pitch to sound wavelength (short wavelength ↔ higher pitch, long wavelength ↔ lower pitch).
2. Identify how amplitude relates to the brightness of light.
3. Explain why prisms separate white light using wavelength-dependent refraction.
4. State that electromagnetic radiation can travel through space and does not require particles traveling through a medium.
5. Recall that radio waves have the longest wavelengths in the electromagnetic spectrum.
6. Use $E_k=\tfrac12mv^2$ to interpret how kinetic energy changes with speed for the pole vaulter situation.
7. Use $E_p=mgh$ to determine gravitational potential energy at maximum height using the correct option values.
8. Recognise hydroelectric energy transfers: gravitational potential energy → turbine motion → electrical energy.
9. Choose a testable magnetic investigation and identify what factors increase magnetic attraction (strength ↑, distance ↓).
10. Select electrostatic force as the non-contact force for the rubbed PVC pipe challenge and choose the correct charging explanation.
11. Recall that resistor symbols are unfilled rectangles and identify actions to increase bulb brightness (voltage ↑, resistance ↓).
12. Calculate current using Ohm’s law for the given 12 V series situation and match the correct option.
13. Choose the correct motor explanation: magnet field interacts with coil field to cause spinning.
14. Order the water cycle correctly as evaporation → condensation → precipitation → runoff.