IB Physics Flashcards: Waves - Wyatt's Notes
IB Physics — Waves Flashcard Deck
Flashcards with spaced repetition. Press Space to flip, then rate your recall (1—4).
Key Concepts
Wave Equation: v = fλ, where v is wave speed, f is frequency, and λ is wavelength. Frequency is determined by the source and does not change when a wave enters a different medium. Wavelength and speed change together to maintain this relationship. Transverse waves have oscillations perpendicular to the direction of travel (light, water waves); longitudinal waves have oscillations parallel to the direction of travel (sound, compression springs). The period T = 1/f is the time for one complete oscillation.
Snell’s Law governs refraction: n₁sinθ₁ = n₂sinθ₂. When light enters a denser medium (higher n), it bends toward the normal. Total internal reflection occurs when light travels from a denser to a less dense medium and the angle of incidence exceeds the critical angle, where sinθc = n₂/n₁. Refractive index n = c/v, where c is the speed of light in vacuum and v is the speed in the medium. Fibre optics use total internal reflection to transmit light over long distances.
Superposition Principle states that when two or more waves overlap, the resultant displacement is the sum of the individual displacements. Constructive interference occurs when waves are in phase (crest meets crest); destructive interference occurs when they are out of phase by half a wavelength (crest meets trough). Path difference determines interference type: constructive when path difference = nλ; destructive when path difference = (n + ½)λ.
Standing Waves form when two identical waves travel in opposite directions. Nodes (zero displacement) and antinodes (maximum displacement) are fixed in position. For a string fixed at both ends, the fundamental frequency has wavelength λ = 2L, where L is the string length. Harmonics occur at integer multiples of the fundamental frequency. Standing waves are responsible for musical tones in instruments and resonance phenomena.
Intuition
Think of waves as ripples on a pond. When two sets of ripples meet, they directly add together — where two crests coincide you get a bigger crest (constructive), and where a crest meets a trough they cancel (destructive). Frequency is like the rhythm of your hand tapping the water: it stays the same no matter how the ripples spread. For Snell’s law, imagine a line of soldiers marching from pavement into mud at an angle: the ones hitting the mud first slow down, causing the line to pivot toward the normal. Standing waves are like a jump rope held at both ends — the rope oscillates but the ends stay fixed.
Why it matters: Waves are everywhere — light, sound, radio signals, earthquakes, and ocean waves. Understanding wave behaviour is essential for telecommunications, medical imaging (ultrasound, MRI), music, and understanding the nature of light itself.
Common Pitfalls
- Thinking frequency changes during refraction. Only wavelength and speed change; the source sets the frequency and it stays constant. This is a very common exam trap — always remember that frequency is the “invariant” quantity.
- Confusing diffraction with refraction: diffraction is the spreading of waves around an obstacle or through a gap; refraction is the bending of waves due to a change in speed between media. Diffraction depends on gap size relative to wavelength; refraction depends on refractive index difference.
- Forgetting that the Doppler effect formula Δf/f = v/c uses the relative speed between source and observer, and the sign depends on whether they are approaching (positive, higher frequency) or receding (negative, lower frequency).
- Assuming that all waves need a medium. Electromagnetic waves (light, radio, X-rays) travel through vacuum. Mechanical waves (sound, water) require a medium.
Cross-References
- Kinematics: Kinematics describes particle motion, and oscillating particles in waves follow kinematic principles.
- Mechanics: Mechanics covers energy transfer, and waves are a mechanism for transferring energy without transferring matter.
- Nuclear and Quantum: Wave-particle duality connects wave phenomena with particle properties — the photoelectric effect and de Broglie wavelength bridge these concepts.
- Electricity: Electromagnetic waves are oscillating electric and magnetic fields, and AC circuits involve wave phenomena.
Advanced Content
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Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.