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Class 7 Science: Light: Shadows and Reflections, 8 practice questions with answers

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These are 8 practice questions on the eleventh chapter of the new NCERT Class 7 Science textbook, Curiosity, called Light: Shadows and Reflections. Each has a short answer and the textbook page it comes from. They cover whether a shining tumbler is a source of light, how dark different shadows are, where a shadow falls, a clock seen in a mirror, a periscope whose top mirror has slipped, the periscope, the kaleidoscope, and why a cycle reflector shines. For the Sun, Moon and planets, see our Class 6 Beyond Earth guide. Try each question before you read the answer.

These questions are our own, drafted with AI help. Every fact was checked against the page it cites by a test script, but no practising teacher has reviewed them yet. If you find a mistake, please tell us.

What the chapter says you need

Facts from the NCERT textbook (Curiosity, Grade 7, Chapter 11, printed pages 153 to 168):

Light and shadows

Question 1. During a power cut on a full-moon night, Meena sees her steel tumbler on the windowsill shining brightly. She says, "My tumbler gives out light, just like the Moon." (a) Is the tumbler a source of light? (b) Is the Moon? (c) Where did the light reaching Meena's eyes from the tumbler first come from?

Answer: (a) no; (b) no; (c) from the Sun. (a) A luminous object gives out its own light; a non-luminous object does not. The tumbler is dark in a dark room. It shines here only because moonlight falls on its shiny surface and is sent on towards Meena's eyes, so it is non-luminous. (b) The Moon is non-luminous too: it gives out no light of its own and only reflects the sunlight that falls on it. (c) So the light took a path from the Sun to the Moon, from the Moon to the tumbler, and from the tumbler to Meena's eyes. Meena is right that the two shine in the same way, but neither is a source of light. (Luminous and non-luminous objects, and the Moon reflecting sunlight, page 154; reflection, page 160.)

Question 2. At noon on a sunny day, three children stand in a row in the school ground. One holds a black cloth umbrella, one a clear plastic umbrella, and one a thin muslin dupatta stretched over her head. (a) Rank the three shadows on the ground from darkest to faintest. (b) Explain the order using what each material does to light.

Answer: (a) the cloth umbrella's shadow is darkest, the dupatta's is lighter, and the clear plastic umbrella's is faintest; (b) opaque, translucent, transparent. (b) The black cloth umbrella is opaque: light does not pass through it, so it makes a dark shadow. The thin muslin is translucent: light passes partly through it, so its shadow is lighter. The clear plastic is transparent: light passes almost completely through it, so it makes at most a faint shadow. (Materials and light, page 157; how dark a shadow is, page 158.)

Question 3. Asha writes with her right hand at a desk at night. The only lamp in the room is behind her right shoulder, and a dark patch keeps falling on the words she is writing. (a) What is the dark patch, and why does it form there? (b) Where could she move the lamp so that the patch no longer falls on her writing?

Answer: (a) the shadow of her hand and arm; (b) in front of her and to her left, for example. (a) Light travels in straight lines. Her hand and arm are opaque and lie in the path of the light from the lamp behind her right shoulder to the page, so they block it, and the page behind them gets no light: that dark patch is the shadow. The page acts as the screen. (b) Where a shadow falls depends on where the lamp, the hand and the page are: move the lamp, and the shadow moves. With the lamp in front of her and to her left, light reaches the page from the side away from her writing hand, so the hand's shadow falls behind it and to the right, off the words. (Shadows, pages 157 to 159.)

Mirrors and images

Question 4. A round wall clock without numbers hangs opposite a large plane mirror. The clock shows exactly 3 o'clock. (a) In the mirror, which way does the hour hand appear to point: to the right, like 3, or to the left, like 9? (b) Is the top of the clock still at the top in the mirror? (c) What time does the mirror seem to show when the clock reads 2 o'clock?

Answer: (a) to the left, like 9; (b) yes; (c) about 10 o'clock. (a) A plane mirror's image is laterally inverted: left appears as right and right as left. The hour hand pointing to the right of the clock appears pointing to the left, so the image looks like 9 o'clock. (b) The image is erect (upright), not upside down, so the top of the clock stays at the top; only left and right swap. (c) At 2 o'clock the hour hand points up and a little to the right; in the mirror it points up and a little to the left, where 10 would be, and the minute hand still points straight up. So the mirror seems to show 10 o'clock. (Images in a plane mirror, pages 161 and 162.)

Question 5. Arjun has made a cardboard periscope: a box bent like the letter Z, with a plane mirror fixed at each bend. He looks into the bottom opening to see over a wall. Then the top mirror slips and turns so that its shiny face points up at the sky. (a) What does Arjun see now? (b) Explain why, using what a mirror does to light.

Answer: (a) a patch of the sky above the periscope; (b) the top mirror now sends light from the sky, not from beyond the wall, down to the lower mirror. (a) He no longer sees what is over the wall; he sees the sky. (b) A mirror changes the direction of the light that falls on it: that is reflection of light. A periscope works because the top mirror turns light coming from the objects in front of it down the box, and the lower mirror turns it again into the viewer's eye. With the top mirror facing up, the light it turns down the box is light arriving from the sky above, so that is what reaches the lower mirror and Arjun's eye. Light still travels in straight lines between the mirrors; only where it starts has changed. (Reflection of light, page 160; the periscope, page 164.)

Question 6. (a) How many mirrors does a simple periscope use, and how are they placed? (b) Name two places where periscopes are used.

Answer: (a) two plane mirrors, set in a box bent into a Z; (b) for example in submarines and tanks. (a) A simple periscope has two plane mirrors fixed at the two bends of a box shaped like the letter Z. Light from the object is reflected by one mirror and then by the other, which lets you see things that are not directly in view. (b) Periscopes are used in submarines and tanks, and by soldiers to look out from their bunkers; you could also use one to see over taller people in front of you. (Periscope, page 164.)

Question 7. Why does a kaleidoscope show a new pattern every time it is turned?

Answer: its three mirrors make many images, including reflections of reflections, which rearrange as it turns. A kaleidoscope has three plane mirror strips joined in a triangle, with broken pieces of coloured bangles or beads at one end. The mirrors form many images, because each mirror also reflects what the others show, so the pieces make a pattern that changes whenever the tube is turned. Designers and artists use kaleidoscopes for ideas for new patterns. (Kaleidoscope, pages 164 and 165.)

Question 8. A cycle has a red reflector at the back. At night it glows brightly when a car's headlights fall on it, but on a dark road with no car around nobody can see it. (a) Is the reflector a luminous object? Explain. (b) How does it make the cycle easier for the driver to see?

Answer: (a) no, it is non-luminous; (b) it sends the headlights' light back towards the driver. (a) A luminous object gives out its own light; a non-luminous one does not. The reflector shines only when light falls on it and is dark without the headlights, so it is non-luminous, like the Moon, which only reflects sunlight. (b) Its shiny surface changes the direction of the light that falls on it, which is reflection of light. Light from the headlights is reflected back towards the car, so the driver sees a bright red spot and knows there is a cycle ahead. (Luminous and non-luminous objects, page 154; reflection of light, page 160.)

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Sources

All opened and read on 2 November 2026. Page numbers are the printed page numbers of the textbook; printed page = PDF page + 152 for this chapter.

The facts are from the textbook pages above. The questions, answers and checks are our own. This guide is general information; follow your teacher and the textbook.