Light: Shadows and Reflections Part 1: MCQs (Q1–Q25)
Part 1 — Light Basics & Shadow Formation (Questions 1–25)
1. Light travels in a straight line in a (single) homogeneous medium. Which statement is correct?
A. Light bends spontaneously in air.
B. Light travels in straight lines in a uniform medium. Correct answer: B
C. Light always moves in a circular path.
D. Light does not move at all.
Explanations:
A) Incorrect — light only changes direction when medium or boundary changes (refraction/reflection).
B) Correct — in a single uniform medium light rays are straight (basic ray model).
C) Incorrect — circular paths are not general behavior for light in uniform media.
D) Incorrect — light clearly propagates.
2. Which of these is a luminous object?
A. Moon (as seen from Earth)
B. Sun Correct answer: B
C. Chair
D. Planet Venus (reflects sunlight)
Explanations:
A) Moon reflects sunlight; it’s non-luminous — incorrect.
B) Correct — Sun produces its own light (luminous).
C) Chair is non-luminous — incorrect.
D) Venus reflects sunlight (appears bright) but is not a source — incorrect.
3. A transparent object is one that:
A. Does not allow any light to pass through.
B. Allows most light to pass through so objects are clearly seen. Correct answer: B
C. Absorbs all light.
D. Scatters light equally in all directions.
Explanations:
A) Opaque objects block light — incorrect.
B) Correct — transparent materials (like glass) transmit light with little scattering.
C) That describes an opaque/black object — incorrect.
D) That describes a translucent/scattering material — incorrect.
4. Which of the following best describes a shadow?
A. Region of complete darkness produced when light is blocked by an opaque object (umbra). Correct answer: A
B. Source of light.
C. Always brighter than surroundings.
D. Produced only by translucent objects.
Explanations:
A) Correct — a shadow is the region behind an opaque object where direct light is blocked.
B) Incorrect — a light source produces light, not a shadow.
C) Incorrect — shadow is darker.
D) Incorrect — translucent objects allow partial light; shadows are mainly from opaque objects.
5. When a small bright source of light illuminates an opaque object, the shadow formed is:
A. Blurry and has large penumbra only.
B. Sharp (distinct) with negligible penumbra (mostly umbra). Correct answer: B
C. Always circular.
D. Invisible.
Explanations:
A) Blurry shadows happen with extended sources.
B) Correct — point (or small) sources produce sharp shadows (mainly umbra).
C) Shape depends on object geometry and light direction — incorrect.
D) Incorrect — shadow is visible.
6. Umbra and penumbra refer to:
A. Umbra = fully lit region; Penumbra = total darkness.
B. Umbra = full shadow; Penumbra = partial shadow. Correct answer: B
C. Names of light sources.
D. Types of mirrors.
Explanations:
A) Reversed definition — incorrect.
B) Correct — umbra is complete shadow, penumbra is partial shadow.
C/D) Incorrect — unrelated terms.
7. If the distance between a small object and a point light source is halved, the size of the shadow on a screen (kept fixed) will:
A. Become larger. Correct answer: A
B. Become smaller.
C. Remain the same.
D. Disappear.
Explanations:
A) Correct — bringing the object closer to source increases angular size of object as seen from source → larger shadow.
B/C/D) Incorrect — opposite or impossible.
8. A sharp shadow indicates that the light source is:
A. Very large and extended.
B. A small or point-like source. Correct answer: B
C. Turning off.
D. Multiple sources at different positions.
Explanations:
A) Large sources produce fuzzy shadows (penumbra) — incorrect.
B) Correct — small/point sources give sharp shadows.
C/D) Incorrect.
9. Which combination will produce the largest penumbra?
A. Small source, tiny object, screen close.
B. Large extended source, object not close to screen — Correct answer: B
C. Point source only.
D. No source.
Explanations:
A) Smaller penumbra — incorrect.
B) Correct — extended sources create wide penumbra; object/screen geometry can increase penumbra.
C) Point source yields negligible penumbra — incorrect.
D) No source = no shadow — incorrect.
10. A pupil in a camera obscura acts like:
A. A lens that magnifies.
B. A pinhole that forms an inverted image — Correct answer: B
C. A source of light.
D. A mirror producing virtual image.
Explanations:
A) Pinhole is not a lens — incorrect.
B) Correct — pinhole camera forms a real inverted image on the opposite wall.
C/D) Incorrect.
11. Sun appears larger in sky than Moon but shadows from Sun are often fuzzy because:
A. Sun is a point source.
B. Sun is an extended source (disc), producing penumbra — Correct answer: B
C. Moon emits light.
D. Shadows don’t depend on source size.
Explanations:
A) Sun is not a point source — incorrect.
B) Correct — finite angular size causes penumbra and partial shadows on Earth.
C/D) Incorrect.
12. During a solar eclipse, observers on Earth can see an annular eclipse (ring) because:
A. Moon emits light.
B. Apparent sizes of Sun and Moon differ—Moon doesn’t fully cover Sun — Correct answer: B
C. Earth moves away.
D. Shadows disappear.
Explanations:
A) Moon reflects light, doesn’t emit — incorrect.
B) Correct — when Moon appears smaller than Sun, a ring of Sun remains (annular eclipse).
C/D) Incorrect.
13. Light ray striking a plane surface and bouncing off obeys which law?
A. Angle of incidence equals angle of reflection. Correct answer: A
B. Angle of incidence equals twice angle of reflection.
C. Light disappears at surface.
D. Reflection does not depend on angle.
Explanations:
A) Correct — fundamental law of reflection.
B/C/D) Incorrect.
14. Diffuse reflection occurs from:
A. A perfectly polished plane mirror only.
B. A rough surface scattering light in many directions. — Correct answer: B
C. A light source.
D. Vacuum.
Explanations:
A) Polished mirror gives regular reflection — incorrect.
B) Correct — rough surfaces cause diffuse reflection and form no clear images.
C/D) Irrelevant.
15. Regular (specular) reflection is produced by surfaces that are:
A. Rough and matte.
B. Smooth and shiny (like a plane mirror). — Correct answer: B
C. Transparent (like clear glass) only.
D. Always black.
Explanations:
A) Produces diffuse reflection — incorrect.
B) Correct — smooth surfaces reflect parallel incident rays into parallel reflected rays.
C/D) Incorrect.
16. The normal at a point on a reflecting surface is:
A. A line parallel to the surface at that point.
B. A line perpendicular to the surface at that point. Correct answer: B
C. The direction of reflected ray always.
D. A curved path.
Explanations:
A) Opposite — incorrect.
B) Correct — normal is perpendicular to tangent plane at point of incidence.
C/D) Incorrect.
17. If the incident ray makes 30° with the normal, the reflected ray makes:
A. 60° with the normal.
B. 30° with the normal. — Correct answer: B
C. 90° with the normal.
D. 0° with the normal.
Explanations:
A) Angle of reflection equals angle of incidence; not doubled — incorrect.
B) Correct — law of reflection.
C/D) Incorrect unless special cases.
18. A shadow can be cast by:
A. Only opaque objects. Correct answer: A
B. Only transparent objects.
C. Only luminous objects.
D. Nothing — shadows are illusions.
Explanations:
A) Correct — opaque objects block light and cast clear shadows.
B) Transparent objects transmit light so no well-defined shadow — incorrect.
C) Luminous object does not cast its own shadow relative to itself; it may cast shadows on others — ambiguous and generally incorrect.
D) Incorrect.
19. Which of the following is TRUE about an image formed by a pinhole camera?
A. Virtual and erect.
B. Real and inverted. — Correct answer: B
C. Lateral inversion occurs.
D. Formed by reflection.
Explanations:
A) Pinhole yields a real inverted image — incorrect.
B) Correct — rays pass through pinhole and cross, producing inverted real image on screen.
C) Lateral inversion is a mirror effect — not pinhole camera.
D) It’s formed by straight-line transmission, not reflection.
20. On a sunny day, your shadow is shortest at:
A. Sunrise.
B. Noon (when Sun is highest). Correct answer: B
C. Sunset.
D. Midnight.
Explanations:
A/C) Shadows are longer when Sun is low — incorrect.
B) Correct — when Sun overhead, shadows are shortest.
D) Midnight Sun absent at most places — incorrect.
21. Which statement is correct about midnight sun (regions near poles in summer)?
A. Sun below horizon always.
B. Sun visible at midnight for several days — continuous daylight — Correct answer: B
C. Shadows vanish entirely all year.
D. No effect on shadows.
Explanations:
A/C/D) Incorrect or misleading.
B) Correct — high latitude summer results in continuous daylight; shadows still form but Sun is low on horizon angle varies.
22. Which material will cast the sharpest shadow under a small bright bulb?
A. Cardboard. Correct answer: A
B. Wax paper (translucent).
C. Clear glass (transparent).
D. Thin tracing paper.
Explanations:
A) Correct — opaque cardboard blocks light producing sharp shadow.
B/C/D) Translucent/transparent let light pass causing faint or no clear shadow — incorrect.
23. If two point sources A and B are very close and shine on an object, the shadow will be:
A. Single sharp outline.
B. Have overlapping penumbras; may have regions of partial shadow. — Correct answer: B
C. Completely absent.
D. Mirror-image only.
Explanations:
A) With two sources, penumbra regions form — incorrect.
B) Correct — multiple sources create complex penumbra/umbra overlap.
C/D) Incorrect.
24. The region where no light from any part of an extended source reaches is the:
A. Antumbra.
B. Umbra. — Correct answer: B
C. Penumbra.
D. Mirror.
Explanations:
A) Antumbra is used in some eclipse geometry but not primary term for full shadow region here — less common for class 7.
B) Correct — umbra = full shadow.
C) Penumbra = partial shadow — incorrect.
D) Irrelevant.
25. A light ray falls on a rough white wall. Which type of reflection occurs?
A. Regular reflection only.
B. Diffuse reflection — Correct answer: B
C. Total internal reflection.
D. No reflection occurs.
Explanations:
A) Regular reflection requires smooth surface — incorrect.
B) Correct — rough wall scatters light in many directions producing diffuse reflection.
C) Total internal reflection occurs at boundaries of denser to rarer medium beyond critical angle — not here.
D) Incorrect.