AP Physics 2 Unit 14 Practice Test

Pick a unit and take a timed, AP^®-style test built only from that unit's questions — with AI feedback on every free-response answer.

unit 9 unit 10 unit 11 unit 12 unit 13 unit 14 unit 15

Waves, Sound, and Physical Optics

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Two ways to practice unit 14

standard

The exam experience, sized to one unit — timed like the real thing

20 Multiple Choice Questions

40 min

1 FRQ – FRQ 1 – Mathematical Routines

24 min

1 FRQ – FRQ 2 – Translation Between Representations

24 min

Sections run back-to-back with the same directions, timers, and scoring as the real exam

Total: 1 hr 28 min

customizable

Pick your own mix of question types

multiple choice questions

free response questions (choose as many as you want)

FRQ 1 – Mathematical Routines · 24 minFRQ 2 – Translation Between Representations · 24 minFRQ 3 – Experimental Design · 24 minFRQ 4 – Qualitative/Quantitative Translation · 24 min

Total: 40 min

How scoring works: multiple choice is scored instantly, free-response answers get point-by-point AI feedback, and your result is a percentage for this unit — not a projected AP^® score.

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AP Physics 2 Unit 14 practice questions

Try 10 multiple-choice questions from Unit 14 here. Pick an answer to see why it's right or wrong, then take the timed test above for a full AP-style set.

Question 1
Unpolarized light of intensity I₀ is incident on a polarizing filter with a vertical transmission axis. The light then passes through a second filter with a transmission axis at an angle θ to the vertical. Which expression represents the final intensity I_f of the transmitted light?
I_f = (1/2)I₀ cos²θ
I_f = I₀ cos²θ
I_f = (1/2)I₀ sin²θ
I_f = (1/2)I₀ cosθ
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Answer: (A)
Deriving the final intensity requires applying the 50% transmission rule for unpolarized light followed by Malus's Law. The first filter reduces the intensity to I₀/2, and the second filter transmits (I₀/2)cos²θ based on the angle relative to the polarization axis.
Question 2
A wave with frequency f travels on a string of linear mass density μ under tension F_T. The wave crosses a boundary onto a second string with linear mass density 9μ under the same tension. Which expression gives the wavelength λ₂ of the wave on the second string?
λ₂ = (1/3f)√(F_T/μ)
λ₂ = (3/f)√(F_T/μ)
λ₂ = (1/9f)√(F_T/μ)
λ₂ = (1/f)√(F_T/μ)
Show answer
Answer: (A)
Deriving the wavelength requires combining the wave speed equation v = √(F_T/μ) with the wave relationship v = λf. Since the density increases by a factor of 9, the speed decreases by a factor of √9 = 3, resulting in a wavelength that is one-third of the original.
Question 3
A laser beam is vertically polarized with average power P_avg and cross-sectional area A. It passes through a polarizing sheet with a transmission axis at an angle φ to the vertical. Which expression represents the transmitted intensity I_t?
I_t = (P_avg/A) cos²φ
I_t = (P_avg/2A) cos²φ
I_t = (P_avg/A) sin²φ
I_t = (P_avg/A) cosφ
Show answer
Answer: (A)
Deriving the intensity requires defining initial intensity as Power/Area and then applying Malus's Law. Since the incident light is already polarized, the transmitted intensity is the initial intensity multiplied by the square of the cosine of the angle.
Question 4
A transverse wave travels at speed $v$ on a string with tension $F_T$ . If the tension is increased to $9F_T$ while keeping the linear mass density constant, what is the new speed of the wave?
$3v$
$9v$
$v/3$
$81v$
Show answer
Answer: (A)
Applying the functional dependence of wave speed on tension ( $v \propto \sqrt{F_T}$ ) shows that multiplying tension by 9 increases speed by a factor of $\sqrt{9} = 3$ .
Question 5
A string of linear mass density $\mu$ supports a wave speed of $60$ m/s. If the string is replaced by one with linear mass density $4\mu$ under the same tension, what is the new wave speed?
15 m/s
30 m/s
120 m/s
240 m/s
Show answer
Answer: (B)
Using the relationship $v \propto 1/\sqrt{\mu}$ , quadrupling the density results in the speed changing by a factor of $1/\sqrt{4} = 1/2$ . Half of 60 m/s is 30 m/s.
Question 6
A mechanical wave has an amplitude $A$ and carries energy $E$ . If the amplitude is adjusted to $0.5A$ , what is the new energy carried by the wave?
$0.25E$
$0.50E$
$1.41E$
$2.00E$
Show answer
Answer: (A)
Applying the functional dependence $E \propto A^2$ , halving the amplitude ( $0.5$ ) changes the energy by a factor of $(0.5)^2 = 0.25$ .
Question 7
A radio wave with frequency $f$ travels through a vacuum at speed $c$ . If the frequency of the source is increased to $4f$ , what is the new speed of the wave in the vacuum?
$0.25c$
$c$
$2c$
$4c$
Show answer
Answer: (B)
Recognizing that the speed of all electromagnetic waves in a vacuum is a universal constant ( $c$ ), regardless of frequency or wavelength.
Question 8
A string with mass $M$ and length $L$ is under tension $F_T$ . A second string with the same mass $M$ but length $2L$ is placed under the same tension $F_T$ . How does the wave speed $v_2$ on the second string compare to the speed $v_1$ on the first?
$v_2 = 0.50 v_1$
$v_2 = 0.71 v_1$
$v_2 = 1.41 v_1$
$v_2 = 2.00 v_1$
Show answer
Answer: (C)
Calculating the new linear density $\mu_2 = M/(2L) = 0.5\mu_1$ . Since $v \propto 1/\sqrt{\mu}$ , the speed changes by $1/\sqrt{0.5} = \sqrt{2} \approx 1.41$ .
Question 9
A sound wave with constant frequency $f$ travels through air. If the air temperature increases, causing the speed of sound to increase by 10%, what is the new wavelength $\lambda_{new}$ in terms of the original wavelength $\lambda_0$ ?
$0.90 \lambda_0$
$1.00 \lambda_0$
$1.10 \lambda_0$
$1.21 \lambda_0$
Show answer
Answer: (C)
Using the functional dependence $\lambda = v/f$ , if $v$ increases by a factor of 1.1 and $f$ is constant, $\lambda$ must also increase by a factor of 1.1.
Question 10
Two strings are made of the same material with density $\rho$ . String B has twice the diameter of String A. If both are under the same tension, what is the ratio of the wave speed on String B to String A ( $v_B/v_A$ )?
$0.25$
$0.50$
$1.00$
$2.00$
Show answer
Answer: (B)
Doubling diameter quadruples the cross-sectional area and thus the linear mass density ( $\mu \propto d^2$ ). Since $v \propto 1/\sqrt{\mu}$ , the speed becomes $1/\sqrt{4} = 1/2$ .

What's on the AP Physics 2 Unit 14 practice test

The standard version takes about 88 minutes and follows the timing and directions of the AP exam, sized to one unit:

20 Multiple Choice Questions (40 minutes)
1 FRQ – FRQ 1 – Mathematical Routines (24 minutes)
1 FRQ – FRQ 2 – Translation Between Representations (24 minutes)

Questions are drawn from 1326 multiple-choice questions and 43 FRQs written for Unit 14, Waves, Sound, and Physical Optics.

Practice AP Physics 2 Unit 14 FRQs

Answer the unit's free-response questions one at a time and get a score on every part.

FRQ 1 – Mathematical Routines (4 questions)
FRQ 2 – Translation Between Representations (6 questions)
FRQ 3 – Experimental Design (18 questions)
FRQ 4 – Qualitative/Quantitative Translation (15 questions)

AP Physics 2 Unit 14 Practice Test

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AP Physics 2 Unit 14 practice questions

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