Waves, Sound, and Physical Optics unit test

A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.

Paper 1 Paper 2 Paper 3

Each paper is built from this unit’s 24 terms and is the same for everyone, so a teacher can assign “Unit 6, Paper 3” and every student sits the identical test. Multiple choice is marked objectively; the written sections you mark yourself against the model answer and rubric.

Suggested time 37 min 34 points0/17 attempted

Coherence

Intensity and the inverse square law

Diffraction and wavelength

Beats

Polarization

Superposition and interference

Wave speed depends on the medium

Effect of slit separation on fringe spacing

Diffraction grating vs double slit

Harmonics on a string

Resonance

Single-slit diffraction

Short answer 1. Define or explain: Thin film thickness for constructive reflection

3 pts

Short answer 2. Define or explain: Standing waves on a string

3 pts

Short answer 3. Define or explain: What changes when a wave enters a new medium

3 pts

Short answer 4. Define or explain: Reflection and phase inversion

3 pts

Free response

10 pts

Monochromatic light of wavelength 550 nm illuminates two narrow slits separated by 0.25 mm. An interference pattern appears on a screen 3.0 m away.

State the condition for a bright fringe in terms of the path difference, and derive the expression for the spacing between adjacent bright fringes on the screen using the small-angle approximation.

Calculate that fringe spacing.

The source is replaced with red light of wavelength 700 nm. State and justify what happens to the spacing.

The slit separation is then doubled. State and justify what happens to the spacing.

Explain what this experiment demonstrates about the nature of light, and identify one experiment whose result cannot be explained by the same model.