Diffraction Grating Quiz: Test Your Understanding of Spectra

12th Grade

Reviewed by Ekaterina Yukhnovich

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By Thames

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Quizzes Created: 10017 | Total Attempts: 9,652,179

| Questions: 20 | Updated: Mar 17, 2026

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1. A diffraction grating is mainly:

One wide slit

Many closely spaced slits

A curved mirror

A prism

Concept: grating structure. A grating contains many slits or grooves. Many sources interfere to produce sharp bright maxima.

Explanation

Concept: grating structure. A grating contains many slits or grooves. Many sources interfere to produce sharp bright maxima.

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About This Quiz

$Diffraction Grating Quiz: Test Your Understanding Of Spectra - Quiz$

This assessment focuses on diffraction grating and its role in producing spectra. It evaluates your understanding of light behavior, interference patterns, and spectral analysis. Mastering these concepts is essential for students and professionals in physics and engineering, enhancing your comprehension of optical phenomena.

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2. A grating produces sharper and brighter maxima than a double slit because many slits reinforce at specific angles.

True

False

Concept: many-slit reinforcement. Constructive interference is much stronger when many slits line up in phase. Off-angle light cancels more strongly, sharpening peaks.

Explanation

Concept: many-slit reinforcement. Constructive interference is much stronger when many slits line up in phase. Off-angle light cancels more strongly, sharpening peaks.

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3. A key use of diffraction gratings is to:

Measure mass

Separate light into its component wavelengths

Increase gravity

Stop reflection

Concept: spectral separation. Different wavelengths satisfy the constructive condition at different angles. This spreads colors and enables spectroscopy.

Explanation

Concept: spectral separation. Different wavelengths satisfy the constructive condition at different angles. This spreads colors and enables spectroscopy.

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4. Gratings separate colors because the angle of bright maxima depends on ______.

Concept: wavelength-dependent angles. The path difference between slits depends on angle. Different wavelengths line up in phase at different angles.

Explanation

Concept: wavelength-dependent angles. The path difference between slits depends on angle. Different wavelengths line up in phase at different angles.

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5. Compared with a single slit, a grating generally produces narrower bright peaks.

True

False

Concept: peak width and number of slits. More slits increases destructive interference away from the maxima. This narrows the bright features.

Explanation

Concept: peak width and number of slits. More slits increases destructive interference away from the maxima. This narrows the bright features.

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6. If a grating has smaller spacing between slits (more lines per mm), it generally produces:

Less spreading of colors

More angular separation between wavelengths

No diffraction

Only reflection

Concept: grating spacing effect. Closer slits increase how quickly path difference changes with angle. This often increases dispersion (color separation).

Explanation

Concept: grating spacing effect. Closer slits increase how quickly path difference changes with angle. This often increases dispersion (color separation).

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7. "Resolution" in spectroscopy means the ability to distinguish two close wavelengths as separate lines.

True

False

Concept: resolution meaning. High resolution separates nearby spectral lines. This is essential for identifying elements and measuring Doppler shifts.

Explanation

Concept: resolution meaning. High resolution separates nearby spectral lines. This is essential for identifying elements and measuring Doppler shifts.

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8. A larger number of illuminated slits generally gives:

Lower resolution

Higher resolution (sharper peaks)

No change

Random results

Concept: more slits improve resolving power. More slits means more coherent contributions. Peaks become sharper, making close lines easier to separate.

Explanation

Concept: more slits improve resolving power. More slits means more coherent contributions. Peaks become sharper, making close lines easier to separate.

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9. Diffraction sets a fundamental limit on how sharply a beam can be focused.

True

False

Concept: diffraction limit. Even perfect optics produce a spread pattern. This limits resolution in telescopes and microscopes.

Explanation

Concept: diffraction limit. Even perfect optics produce a spread pattern. This limits resolution in telescopes and microscopes.

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10. The central bright spot from a circular aperture diffraction pattern is called the:

Trough

Airy disk

Node

Echo

Concept: airy disk. The airy disk comes from diffraction through a circular aperture. Its size depends on wavelength and aperture diameter.

Explanation

Concept: airy disk. The airy disk comes from diffraction through a circular aperture. Its size depends on wavelength and aperture diameter.

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11. Shorter wavelengths generally produce smaller diffraction patterns (narrower spreading) for the same aperture.

True

False

Concept: wavelength and diffraction angle. Diffraction angle scales with wavelength relative to aperture. Using shorter wavelength reduces spreading and improves resolution.

Explanation

Concept: wavelength and diffraction angle. Diffraction angle scales with wavelength relative to aperture. Using shorter wavelength reduces spreading and improves resolution.

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12. A telescope’s resolving power improves most directly when you:

Use a smaller lens

Use a larger aperture

Use warmer air

Use a dimmer star

Concept: aperture controls diffraction limit. Larger apertures reduce diffraction angle, narrowing the image spot. That makes it easier to distinguish close objects.

Explanation

Concept: aperture controls diffraction limit. Larger apertures reduce diffraction angle, narrowing the image spot. That makes it easier to distinguish close objects.

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13. A diffraction grating can be used to identify chemical elements from their spectral lines.

True

False

Concept: spectroscopy application. Each element has characteristic emission/absorption lines. Gratings spread these wavelengths so they can be measured.

Explanation

Concept: spectroscopy application. Each element has characteristic emission/absorption lines. Gratings spread these wavelengths so they can be measured.

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14. If two spectral lines are very close together, improving resolution is helped by:

Fewer slits illuminated

More slits illuminated

Wider slit spacing always

Lower coherence

Concept: resolution depends on effective grating size. More illuminated slits increases peak sharpness. Sharper peaks separate close lines better.

Explanation

Concept: resolution depends on effective grating size. More illuminated slits increases peak sharpness. Sharper peaks separate close lines better.

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15. Coherent light sources make diffraction patterns clearer and more stable.

True

False

Concept: coherence and interference stability. Coherence keeps phase relationships steady across the slits. This prevents fringe patterns from washing out.

Explanation

Concept: coherence and interference stability. Coherence keeps phase relationships steady across the slits. This prevents fringe patterns from washing out.

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16. In many diffraction setups, the bright peaks are called interference ______.

Concept: maxima terminology. Maxima are locations of strong constructive interference. Minima are where destructive interference reduces intensity.

Explanation

Concept: maxima terminology. Maxima are locations of strong constructive interference. Minima are where destructive interference reduces intensity.

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17. Diffraction and interference are closely linked: diffraction patterns are built from interference of many wave contributions.

True

False

Concept: unified wave explanation. Diffraction can be viewed as interference from different parts of a wavefront. Gratings make this especially clear with many slits.

Explanation

Concept: unified wave explanation. Diffraction can be viewed as interference from different parts of a wavefront. Gratings make this especially clear with many slits.

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18. Which is a correct reason gratings are preferred over prisms for many measurements?

Prisms can’t bend light

Gratings can produce very high resolution and accurate wavelength separation

Gratings only work underwater

Gratings stop light completely

Concept: precision wavelength measurement. Gratings produce sharp peaks and allow precise angle–wavelength relationships. This can yield high spectral resolution.

Explanation

Concept: precision wavelength measurement. Gratings produce sharp peaks and allow precise angle–wavelength relationships. This can yield high spectral resolution.

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19. If you change the wavelength of light, the angles of the grating maxima change.

True

False

Concept: angle depends on wavelength. Constructive interference condition depends on wavelength. That’s why different colors appear at different angles.

Explanation

Concept: angle depends on wavelength. Constructive interference condition depends on wavelength. That’s why different colors appear at different angles.

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20. The best overall summary is:

A grating is just a mirror

Diffraction gratings use many slits to create sharp interference maxima, enabling wavelength separation and high resolution

More slits makes patterns blurrier

Diffraction is unrelated to resolution

Concept: grating and resolution summary. Many-slit interference sharpens peaks. This improves resolving power and makes gratings powerful tools in optics.

Explanation

Concept: grating and resolution summary. Many-slit interference sharpens peaks. This improves resolving power and makes gratings powerful tools in optics.

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