Progressive Waves and interferences practice questions
Use Clevolab for progressive practice in waves and interferences. This page shows what the topic covers, what skills the current set targets, and a few real examples from the reviewed question bank.
About this topic
Clevolab treats waves and interferences as repeated practice with explanation, not just answer checking. This page is designed to make the topic legible before you open the app.
The current Progressive set covers superposition, diffraction, standing waves, and interference patterns. 138 reviewed questions currently published for this page.
What you can practise
- Wave behaviour
- Superposition
- Interference patterns
- Standing waves
- Diffraction reasoning
Real sample questions from the current set
These examples come from the reviewed questions currently stored for this topic. They are here so the page shows the actual flavour of Clevolab, not just a summary.
Sample question
Total internal reflection occurs when light
- AEnters a denser medium at small incidence angleAnswer option
- BTravels from low to high refractive index at any angleAnswer option
- CHits a mirror at any angleAnswer option
- DTravels from higher to lower $n$ with incidence angle above the critical angleCorrect answer
Why this answer is right
TIR requires going from higher to lower refractive index and $\theta_i>\theta_c$, where $\sin\theta_c=n_2/n_1$ with $n_1>n_2$.
Total internal reflection occurs when a refracted ray cannot exist in the second medium, so the incident light is completely reflected back into the first medium.
Sample question
A galaxy receding slowly from Earth shows which spectral change?
- AHigher frequency (blueshift)Answer option
- BNo change in wavelengthAnswer option
- CShorter wavelength and higher frequencyAnswer option
- DLonger wavelength and lower frequencyCorrect answer
Why this answer is right
Relativistic Doppler for recession increases observed wavelength (redshift) and decreases frequency. For $v\ll c$, $\Delta\lambda/\lambda\approx v/c$ and $f$ drops correspondingly.
When a light source moves away from you, each successive wave crest has farther to travel before it is emitted, so the spacing between crests you receive is stretched. This is the Doppler redshift for light. The exact relativistic relations are $f_{\mathrm{obs}} = f_{\mathrm{emit}}\sqrt{\frac{1-\beta}{1+\beta}}$ and $\lambda_{\mathrm{obs}} = \lambda_{\mathrm{emit}}\sqrt{\frac{1+\beta}{1-\beta}}$, where $\beta = v/c$. For slow recession $v \ll c$ (that is, $\beta \ll 1$), first-order expansion gives $f_{\mathrm{obs}} \approx f_{\mathrm{emit}}(1-\beta)$ and $\lambda_{\mathrm{obs}} \approx \lambda_{\mathrm{emit}}(1+\beta)$, so frequency decreases while wavelength increases. Because the speed of light is fixed, $c = f\lambda$, any increase in $\lambda$ must come with a proportional decrease in $f$. Astronomers often express this as a redshift $z = \frac{\lambda_{\mathrm{obs}}-\lambda_{\mathrm{emit}}}{\lambda_{\mathrm{emit}}} \approx \frac{v}{c}$ for $v \ll c$, which is positive for recession. Therefore the observed spectrum shifts to longer wavelength and lower frequency.
Sample question
A supersonic source moves at speed $v$ in a medium where sound speed is $c$. What is the Mach cone half-angle $\mu$?
- A$\cos\mu=c/v$Answer option
- B$\tan\mu=v/c$Answer option
- C$\mu=c/v$Answer option
- D$\sin\mu=c/v$Correct answer
Why this answer is right
Constructive interference occurs on a cone where the source has advanced by $v t$ while wavefronts have radius $ct$. Geometry gives $\sin\mu=c/v$.
For a source moving supersonically with $v>c$, each disturbance emitted at an earlier time $t$ has expanded into a sphere of radius $ct$ centered at the source’s past position, while the source itself has moved a distance $vt$ along its path.
How this page fits into Clevolab
Clevolab is broader than any one exam mode. GCSE and A-level pages are useful entry points, while the wider project is about sharpening understanding through repeated topic practice.