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### Descriptive Statements:

- Demonstrate knowledge of the characteristics and types of waves.
- Demonstrate knowledge of wave propagation and how waves transfer energy and momentum.
- Describe factors that affect the speed of a wave in different media.
- Solve problems involving wave speed, frequency, and wavelength.
- Analyze the reflection, refraction, and polarization of waves.
- Apply the superposition principle to analyze wave phenomena.
- Demonstrate knowledge of the Doppler effect.
- Demonstrate knowledge of the relationships between a sound wave and the human perception of sound.
- Solve problems involving standing waves, resonance, and sounds produced by waves on a string or in a pipe, given various boundary conditions.
- Solve problems involving the intensity of sound and the decibel scale.

### Sample Item:

A person standing 85 m from a wall shouts and hears the echo 0.50 s later. The person
then plays a note of 440 Hz on a flute. What is the wavelength of the note in air?

- 0.39 m
- 0.77 m
- 1.3 m
- 2.6 m

Correct Response and Explanation (Show Correct ResponseHide Correct Response)

**B.** This question requires the examinee to solve a problem involving wave
speed, frequency, and wavelength. Since the person hears the echo of the shout after
0.50 s, the speed of sound is 170 m/0.50 s or 340 m/s. Since *v = f*λ, the
wavelength is λ = 0.77 m170 m slash 0.50 s or 340 m slash s. Since *v equals f* lambda, the
wavelength is lambda equals 0.77 m.

### Descriptive Statements:

- Demonstrate knowledge of the electromagnetic spectrum and the production and transmission of electromagnetic waves.
- Apply the ray model of light and the thin lens equation to analyze characteristics of lenses and mirrors.
- Solve problems using Snell's law in various situations.
- Apply the wave model of light to describe phenomena such as interference, dispersion, diffraction, and polarization.
- Apply properties of light to describe the operation of optical devices such as filters, magnifying devices, and diffraction gratings.
- Describe various phenomena (e.g., electron transitions, atomic spectra, operation of a laser) using the photon model of light.

### Sample Item:

A light-emitting diode (LED) on a consumer device emits 0.020 W of light of wavelength
λ = 650 × 10^{−9} m.lambda equals 650 times 10 superscript negative 9 m. Which of the following expressions equals the number
of photons emitted by the LED per second in terms of Planck's constant (*h*) and the speed
of light (*c*)?

^{0.020λ}/_{hc}0.020 lambda over *hc*

^{0.020hc}/_{λ}0.020*hc*over lambda

^{0.020hλ}/_{c}0.020*h* lambda over *c*

^{0.020}/_{hcλ}0.020 over *hc* lambda

Correct Response and Explanation (Show Correct ResponseHide Correct Response)

**A.** This question requires the examinee to describe various phenomena
using the photon model of light. The energy of a single photon is given by
*E = hf**E equals hf*. For light, *c = f*λ, so *E = *^{hc}/_{λ}*c equals f* lambda, so *E equals* *hc* over lambda;.
Since the power of the LED is 0.020 W, dividing the power by the energy of a single
photon gives the number of photons emitted per second.