Physics 1 · CED Unit 7: Simple Harmonic Motion and Waves · 14 min read · Updated 2026-05-11
AP Physics 1 Wave Types and Basic Properties — AP Physics 1
AP Physics 1 · CED Unit 7: Simple Harmonic Motion and Waves · 14 min read
1. Wave Definition and Classification Schemes★☆☆☆☆⏱ 3 min
A wave is a disturbance that propagates through space or a medium, transferring energy from one location to another without any net transfer of matter. This foundational topic makes up ~2-4% of your total AP Physics 1 exam score, and underlies all other wave topics in Unit 7. Waves are classified along two main axes for AP exam questions.
Exam tip: AP exam questions often mix classification axes. Always read the question carefully to confirm which classification it asks for, don’t assume.
2. Core Measurable Properties of Periodic Waves★★☆☆☆⏱ 4 min
All repeating (periodic) waves share four core measurable properties that are used for all wave analysis in AP Physics 1. These properties are linked by simple relationships that are frequently tested on the exam.
f = \frac{1}{T} \quad \text{and} \quad T = \frac{1}{f}
Exam tip: When asked for wavelength from a given distance between crests, always count how many full wavelengths are between the given points, don’t automatically assume the distance given is a single wavelength.
3. The Universal Wave Speed Formula★★☆☆☆⏱ 4 min
Wave speed is the speed at which the wave disturbance propagates through the medium. The relationship between wave speed, frequency, and wavelength holds for all periodic waves, regardless of type, which is why it is called the universal wave formula.
v = f \lambda
A critical AP-tested rule: for mechanical waves in a given medium, wave speed depends only on the properties of the medium, not on frequency or amplitude. If you increase the frequency of a wave in a fixed medium, speed stays the same, so wavelength decreases proportionally to keep the formula balanced. When a wave crosses from one medium to another, frequency (set by the wave source) remains constant, while speed and wavelength change.
Exam tip: Remember that frequency is determined by the source of the wave, while speed is determined by the medium. When a wave crosses from one medium to another, $f$ stays the same, $v$ changes, so $\lambda$ changes.
4. AP-Style Practice Problems★★★☆☆⏱ 3 min
Common Pitfalls
Why: Students confuse the graphical representation of longitudinal wave pressure with the actual direction of particle displacement.
Why: Students confuse source properties (frequency) with medium properties (speed) and incorrectly extrapolate from $v = f\lambda$ that higher $f$ means higher $v$.
Why: Students forget wavelength is the length of one full cycle, and confuse half a cycle with a full cycle.
Why: Students see water moving toward shore and assume the water itself travels from the open ocean to the coast.
Why: Students mix up the relationship between amplitude and energy with linear relationships for other wave properties.