Light: Shadows and Reflections — Mastery

Q1. Objects that do not emit their own light are called

• A. luminous objects.
• B. translucent objects.
• C. opaque objects.
• D. non-luminous objects.

Q2. The earliest form of artificial lighting created by humans was

• A. an electric bulb.
• B. fire.
• C. a candle.
• D. a kerosene lantern.

Q3. Ravi shines a low-power laser pointer through a beaker of water in which a drop of milk has been added. He observes that the beam

• A. bends sharply downwards in the water.
• B. splits into seven colours inside the water.
• C. follows a straight path inside the water.
• D. disappears completely after entering the water.

Q4. In Table 11.1 of Activity 11.3, Priya predicts that thick cloth will let light pass partially. She actually finds that no light passes. Her prediction was

• A. incorrect; thick cloth is opaque, so light does not pass.
• B. correct; thick cloth is translucent like tracing paper.
• C. correct; thick cloth lets full light through.
• D. incorrect; thick cloth is luminous.

Q5. From the list — clear window glass, cardboard, tracing paper, butter paper, polished wood — which set lists ONLY translucent materials?

• A. Clear window glass, polished wood.
• B. Tracing paper, butter paper.
• C. Cardboard, polished wood.
• D. Clear window glass, cardboard.

Q6. In our daily life, the screen on which we observe a shadow can be

• A. only a white sheet of paper.
• B. only a polished mirror.
• C. only a glass window.
• D. any surface such as a wall, the floor or the ground.

Q7. Asha holds an opaque book straight in the torch beam and sees a rectangular shadow. She then tilts the book at an angle. The shadow

• A. stays rectangular and of the same size.
• B. becomes circular.
• C. changes its shape — appears narrower than before.
• D. disappears completely.

Q8. A figure shows a boy standing in the Sun with four images of his shadow. The correct image is the one in which the shadow is

• A. above the boy's head, in the direction of the Sun.
• B. to one side of the boy, perpendicular to the Sun.
• C. missing because shadows do not form outdoors.
• D. behind the boy on the ground, in the direction opposite to the Sun.

Q9. Shadow puppetry, mentioned in the Fascinating Facts of Chapter 11, is part of which Indian state's cultural heritage as 'Charma Bahuli Natya'?

• A. Maharashtra.
• B. Andhra Pradesh.
• C. Karnataka.
• D. Kerala.

Q10. In Activity 11.6, a comb is used to make a thin slit of light from a torch which then strikes a plane mirror. The thin beam after the mirror

• A. continues in the same direction.
• B. changes its direction — it is reflected.
• C. passes through the mirror to the other side.
• D. splits into many colours.

Q11. In Activity 11.7, what is correctly called the 'object' and what is the 'image'?

• A. The pen behind the mirror is the object; the pen in front is the image.
• B. The pen behind the mirror is the image; the pen in front is the object.
• C. Both the pen in front and the pen behind are objects.
• D. Neither is correctly called an object or an image.

Q12. An upright image is described as

• A. an inverted image.
• B. an erect image.
• C. a magnified image.
• D. a coloured image.

Q13. A student writes their name on paper and holds it before a plane mirror so the paper is parallel to the mirror. In the image they see

• A. the name appears upside down with letters in correct left-right order.
• B. the name appears unchanged.
• C. the colour of the ink changes.
• D. the name appears laterally inverted — the letters look reversed left to right.

Q14. A pinhole camera is best defined as

• A. a curved mirror that reflects an image of distant objects.
• B. a glass lens fitted in a wooden box.
• C. a device in which light rays from an object pass through a tiny hole and form an image on a screen.
• D. a translucent paper that filters sunlight.

Q15. In an activity (a simple pinhole camera with cardboard and screen), the student observes the image of a candle flame. The most surprising observation the student is expected to record is that the image

• A. is upside down (inverted) compared to the actual flame.
• B. is brighter than the candle flame.
• C. is missing — no image forms.
• D. appears coloured even when the room is dark.

Q16. In Activity 11.10, why are two cardboard boxes used — one sliding inside the other — instead of a single box?

• A. To increase the size of the pinhole.
• B. To use less cardboard.
• C. To allow two students to look at the image together.
• D. To slide the screen forwards or backwards until a clear image is obtained on the tracing paper.

Q17. Why does a periscope use TWO plane mirrors instead of just one?

• A. Two mirrors make the image brighter.
• B. Two mirrors change the colour of the image.
• C. Two mirrors absorb stray light.
• D. Two mirrors bend the path of light around an obstacle so we can see something not directly visible.

Q18. A periscope can be used by a short student to

• A. look ahead even when a taller friend is standing in front.
• B. make the room appear larger.
• C. see through walls.
• D. measure the height of a tree.

Q19. Assertion (A): Each time the kaleidoscope is turned, a different pattern is seen. Reason (R): The coloured pieces inside the kaleidoscope shift their position when the tube is turned, and multiple reflections in the three mirrors create new patterns.

• A. Both A and R are true, and R is the correct explanation of A.
• B. Both A and R are true, but R is NOT the correct explanation of A.
• C. A is true, R is false.
• D. A is false, R is true.

Q20. Designers and artists often use kaleidoscopes to

• A. test new mirrors.
• B. get ideas for new patterns.
• C. measure the brightness of light.
• D. make periscopes.

Q21. In Activity 11.1, three matchboxes are arranged so the holes are at the same height and in a line. A torch is placed on one side and a cardboard screen on the other. A bright spot is seen because

• A. the light from the torch follows the straight line of the holes and reaches the screen.
• B. the matchboxes glow when warm.
• C. the cardboard absorbs and re-emits light.
• D. the torch reflects from the inner sides of the matchboxes.

Q22. Which row correctly pairs the material with its classification?

• A. Clear glass — opaque; tracing paper — transparent; cardboard — translucent.
• B. Clear glass — transparent; tracing paper — translucent; cardboard — opaque.
• C. Clear glass — translucent; tracing paper — opaque; cardboard — transparent.
• D. Clear glass — luminous; tracing paper — opaque; cardboard — non-luminous.

Q23. A Class 7 Science teacher wants Class 7 students to genuinely understand the difference between transparent, translucent and opaque materials. Which approach is the MOST effective?

• A. Asking students to memorise the three definitions and write them five times each.
• B. Showing one slideshow with photographs of each material type.
• C. Telling students the answer directly and then giving a quick quiz.
• D. Running Activity 11.3 — students first predict, then observe with a torch and various materials, and then explain the difference using their own data.

Q24. Many Class 7 children believe the Moon shines by its own light. Which is the BEST classroom strategy to address this misconception?

• A. Telling children loudly that they are wrong.
• B. Linking back to 'Beyond Earth' (Class 6) where they learnt that solar-system bodies shine by reflecting the Sun's light, and discussing why the Moon is therefore non-luminous.
• C. Skipping the topic to avoid confusion.
• D. Asking children to copy the definition of 'luminous' from the textbook.

Q25. A teacher wants to assess whether a Class 7 child has truly understood that 'light travels in a straight line'. Which evidence is the STRONGEST?

• A. The child can recite the definition word-for-word.
• B. The child copies the chapter heading neatly.
• C. The child draws a torch and a candle in their notebook.
• D. The child correctly predicts who will see the candle in Fig. 11.16 and explains the answer using rectilinear propagation.

Q26. In Activity 11.5, Ravi tilts a polished steel plate in sunlight and observes the bright spot on a wall move. The best conclusion is that

• A. tilting the mirror changes the direction in which the reflected light travels.
• B. the mirror generates new light when tilted.
• C. the wall absorbs more light when the mirror is tilted.
• D. the colour of the mirror changes with tilt.

Q27. A plane mirror is one that is

• A. curved inward like a spoon's inner side.
• B. always coloured silver.
• C. always made of plastic.
• D. flat and not curved.

Q28. A student is asked whether a small piece of a plane mirror can form an image of a very tall tree. The best prediction is that the small mirror

• A. magnifies the tree, so the full image fits.
• B. cannot form any image at all.
• C. shows only a small portion of the tree at a time, even though the full image of the tree exists in space.
• D. burns the tree's reflection on the wall.

Q29. A student is asked to sketch the outline of the image of a tree formed by a pinhole camera. The correct sketch shows the tree

• A. exactly the same way as the original.
• B. doubled — two trees side by side.
• C. missing — only a dark patch.
• D. upside down compared to the original.

Q30. Reflection happens not only at mirrors but at any

• A. opaque object such as cardboard.
• B. translucent material such as tracing paper.
• C. transparent material such as clear glass.
• D. shiny surface that changes the direction of light falling on it.