⚛️ Physics · Topic 2 of 10
Start with the study notes on Light, Shadows & Reflection (definitions, examples and a quick revision), then work through 60 practice questions, each with the correct answer and a clear explanation of why it is right. When you are ready, take this topic as an interactive quiz to test yourself.
Topic overview
We see an object only when light from it enters our eyes. In complete darkness nothing is visible, even with our eyes wide open.
Luminous objects give out their own light. Non-luminous objects do not; we see them because they reflect light into our eyes.
Examples:
Remember: The Moon is non-luminous. It shines only because it reflects sunlight.
Materials are grouped by how much light they let through:
Example: Bathroom windows often use frosted glass. Light comes in, but nobody can see clearly inside.
Light travels in straight lines. This is called the rectilinear propagation of light.
Examples:
A shadow is the dark area formed when an opaque object blocks light.
To form a shadow, you need three things:
A shadow is always dark and shows only the outline of the object, not its colour or details. It forms on the side away from the light.
Examples:
An eclipse happens when the shadow of one body falls on another.
A pinhole camera is a box with a tiny hole at one end and a screen at the other. Light from an object passes straight through the hole and forms an image on the screen.
The image is upside down (inverted), because rays from the top of the object travel straight to the bottom of the screen, and rays from the bottom travel to the top.
Example: The round patches of light under a leafy tree are pinhole images of the Sun, made by the small gaps between the leaves.
Reflection is the bouncing back of light when it falls on a surface. Smooth, shiny surfaces give clear images; rough surfaces scatter the light.
Example: You can see your face in a mirror or in still water, but not in rippling water.
A plane mirror is a flat mirror. Its image is:
Examples:
Refraction is the bending of light when it passes from one transparent material into another, such as from water into air.
Examples:
Dispersion is the splitting of white light into seven colours. A glass prism does this.
VIBGYOR: Violet, Indigo, Blue, Green, Yellow, Orange, Red
Example: A rainbow forms when raindrops refract, reflect and disperse sunlight. Red is on the outer (top) edge and violet on the inner edge.
| Misconception | Correct understanding |
|---|---|
| The Moon makes its own light. | The Moon is non-luminous; it reflects sunlight. |
| A red ball casts a red shadow. | A shadow is dark whatever the object's colour, because it is just where light is blocked. |
| A plane mirror turns your image upside down. | A plane mirror only swaps left and right. A pinhole camera is what turns images upside down. |
| Reflection and refraction are the same thing. | Reflection is light bouncing back; refraction is light bending as it enters a new material. |
| A mirror image can be caught on a screen. | A plane mirror's image is virtual. Only a real image, like a pinhole camera's, appears on a screen. |
Why can't we see anything in a completely dark room?
Seeing needs light from objects to enter our eyes, and there is none.
Classify clear glass, butter paper and wood.
Transparent, translucent and opaque.
What three things are needed to form a shadow?
A light source, an opaque object and a screen or surface.
Why is the image in a pinhole camera upside down?
Light travels in straight lines, so rays from the top of the object reach the bottom of the screen, and rays from the bottom reach the top.
Why is AMBULANCE written back-to-front on ambulances?
A mirror swaps left and right, so drivers ahead read it correctly in their mirrors.
Why do vehicles use convex mirrors as rear-view mirrors?
They give a wider view of the road behind.
Why does a pencil in water look bent?
Light from the pencil bends (refracts) as it passes from water into air.
Key takeaway: Light travels in straight lines: blocked, it makes shadows; bounced back, it makes reflections; bent, it makes refraction and rainbows.
Notes written by Velnov for Class 6–8 students, following the topics of the NCERT science syllabus.
Q1. easy
An object that gives out (emits) its own light is called:
Answer: A — Luminous
Luminous objects produce their own light - like the sun, a burning candle, a bulb or a firefly. Non-luminous objects (like the moon or a book) do not.
Q2. easy
The moon appears bright at night. The moon is a:
Answer: A — Non-luminous object (it reflects the sun's light)
The moon does not make its own light; it shines because it reflects sunlight. So the moon is a non-luminous object.
Q3. easy
Objects through which we can see clearly are called:
Answer: A — Transparent
Transparent objects (like clear glass, air, clean water) allow light to pass through them, so we can see through them clearly.
Q4. easy
Objects through which we CANNOT see at all are called:
Answer: A — Opaque
Opaque objects (like wood, a wall, metal, a book) do not allow light to pass through, so we cannot see through them. Opaque objects form shadows.
Q5. medium
Objects through which we can see only partially/blurred (light passes partly) are called:
Answer: A — Translucent
Translucent objects (like frosted glass, oiled paper, or a thin cloth) allow only some light through, so objects behind them appear blurred.
Q6. medium
Light travels in a:
Answer: A — Straight line
Light travels in straight lines. This is called the rectilinear propagation of light, and it explains why shadows form and why we cannot see around corners.
Q7. medium
A shadow is formed when an opaque object comes in the path of:
Answer: A — Light
When an opaque object blocks light travelling in a straight line, a dark region (shadow) forms on the side away from the light source.
Q8. medium
To form a shadow, we need: a source of light, an opaque object, and:
Answer: A — A screen (surface) to catch the shadow
Three things are needed for a shadow: a source of light, an opaque object to block the light, and a screen or surface (like a wall or the ground) on which the shadow falls.
Q11. medium
A device that uses a small hole to form an (inverted) image of an object is called a:
Answer: A — Pinhole camera
A pinhole camera forms an inverted (upside-down) image on a screen because light travels in straight lines through the tiny hole. It demonstrates the rectilinear propagation of light.
Q13. medium
When light falls on a mirror and bounces back, this is called:
Answer: A — Reflection
Reflection is the bouncing back of light when it strikes a smooth, shiny surface like a mirror. This is why we can see our image in a mirror.
Q14. medium
The image formed by a plane (flat) mirror is:
Answer: A — Erect (upright) and of the same size as the object
A plane mirror forms an image that is erect (the right way up), virtual, and the same size as the object. However, it is laterally inverted (left and right appear swapped).
Q17. medium
A device using two mirrors to see over obstacles (like from a submarine or over a crowd) is a:
Answer: A — Periscope
A periscope uses two plane mirrors (usually at 45 degrees) to reflect light and let you see objects that are above or behind an obstacle. Submarines use periscopes.
Q19. medium
Which surface reflects light best to give a clear image?
Answer: A — A smooth, shiny (polished) surface
Smooth, shiny surfaces (like a mirror or still water) reflect light in a regular way, giving clear images. Rough surfaces scatter light in all directions and do not form clear images.
Q21. medium
A shadow is longest during which part of the day?
Answer: A — Early morning and late evening (when the sun is low)
When the sun is low in the sky (morning and evening), light hits objects at a slanting angle, casting long shadows. At noon, the sun is high overhead, so shadows are shortest.
Q22. medium
A shadow is shortest at:
Answer: A — Noon (midday), when the sun is highest
At noon the sun is highest in the sky, so light falls almost straight down and shadows are shortest. As the sun moves lower, shadows grow longer.
Q23. medium
Which of these is a natural source of light?
Answer: A — The Sun
The Sun and stars are natural sources of light. A torch, candle, bulb and tube light are man-made (artificial) sources.
Q25. medium
In complete darkness, even with our eyes open, we cannot see objects because:
Answer: A — There is no light to enter our eyes
Seeing requires light. In total darkness there is no light coming from objects into our eyes, so we cannot see them, no matter how wide our eyes are open.
Q28. medium
The bending of light when it passes from one transparent medium to another (like from air to water) is called:
Answer: A — Refraction
Refraction is the change in direction (bending) of light as it passes from one medium to another (e.g., air to water). This is why a straw in a glass of water looks bent.
Q30. medium
White light (like sunlight) is actually made up of:
Answer: A — Seven colours
Sunlight (white light) is a mixture of seven colours: Violet, Indigo, Blue, Green, Yellow, Orange and Red (remembered as VIBGYOR). A prism can split white light into these colours.
Q33. medium
Which colour of light is at the TOP of a rainbow?
Answer: A — Red
In a rainbow, red appears on the outer/top edge and violet on the inner/bottom edge. The order from top is Red, Orange, Yellow, Green, Blue, Indigo, Violet.
Q34. medium
The correct order of colours in white light (VIBGYOR) starting from Violet is:
Answer: A — Violet, Indigo, Blue, Green, Yellow, Orange, Red
VIBGYOR stands for Violet, Indigo, Blue, Green, Yellow, Orange, Red - the seven colours of white light in order.
Q35. medium
A mirror whose reflecting surface is flat is called a:
Answer: A — Plane mirror
A plane mirror has a flat reflecting surface. Curved mirrors are either concave (curved inward) or convex (curved outward).
Q38. medium
Which of these can pass through a transparent object?
Answer: A — Light passes through fully
Transparent objects allow light to pass through completely, so we can see clearly through them (e.g., clear glass, water, air).
Q39. medium
Frosted glass in a bathroom window is an example of a ______ material.
Answer: A — Translucent
Frosted glass lets some light through but not a clear view, so it is translucent. This gives privacy while still letting light in.
Q41. medium
Why can we NOT see around a corner?
Answer: A — Because light travels in straight lines and cannot bend around corners
Since light travels in straight lines, it cannot bend around a corner to reach our eyes. That is why we cannot see objects hidden behind a wall or corner directly.
Q43. medium
A shadow puppet show works because the puppets are:
Answer: A — Opaque and block light to form shadows on a screen
Shadow puppets are opaque, so they block light behind them and cast dark shadows onto a translucent screen, creating the images the audience sees.
Q45. medium
Which of the following is a luminous object?
Answer: A — A glowing electric bulb
A glowing bulb produces its own light, so it is luminous. A table, the moon and a mirror are non-luminous - they only reflect light.
Q47. medium
If you stand 1 metre in front of a plane mirror, your image appears to be:
Answer: A — 1 metre behind the mirror (2 m from you)
In a plane mirror, the image forms as far behind the mirror as the object is in front. So your image appears 1 m behind the mirror, i.e., 2 m away from you.
Q49. medium
Sunlight passing through a small gap between leaves can make circular patches of light on the ground because:
Answer: A — The gaps act like pinholes forming images of the round sun
Small gaps between leaves act like pinhole cameras, forming faint round images of the sun on the ground - a real-world example of pinhole imaging.
Q51. medium
A mirror changes the DIRECTION of light by:
Answer: A — Reflecting it
A mirror reflects light, bouncing it back and changing its direction. This property is used in periscopes and to redirect light beams.
Q53. medium
The primary source of light for the Earth is the:
Answer: A — Sun
The Sun is the Earth's main natural source of light and heat. It is a luminous star that makes life on Earth possible.
Q55. medium
Which instrument uses lenses to see very distant objects like stars and planets?
Answer: A — Telescope
A telescope uses lenses (or mirrors) to make distant objects like stars, planets and the moon appear larger and clearer. A microscope is used to see very tiny, close objects.
Q57. medium
A butterfly, a peacock's feather and a soap bubble show many colours mainly because of:
Answer: A — The splitting/interference of white light (dispersion effects)
The shimmering colours of soap bubbles, peacock feathers and some insect wings arise from white light being split and combined by their fine surface structures - related to dispersion and interference of light.
Q58. medium
Which of these lets NO light pass through it?
Answer: A — A brick wall (opaque)
A brick wall is opaque and blocks light completely. Clear glass, air and clean water are transparent and allow light to pass through.
Q60. medium
A shadow is formed on the ground because sunlight is blocked by an:
Answer: A — Opaque object
Shadows form when an opaque object blocks light travelling in straight lines, leaving a dark region on the surface behind it.
Q9. hard
What is the colour of a shadow (regardless of the colour of the object)?
Answer: A — Always dark/black
A shadow is always dark (black), no matter what colour the object is, because it is simply a region where light has been blocked. A shadow shows only the outline (shape) of the object, not its colour or details.
Q10. hard
A shadow tells us about the object's:
Answer: A — Shape (outline) only
A shadow shows only the outline or shape of the object. It cannot tell us the object's colour, surface details, or what it is made of.
Q12. hard
The image formed by a pinhole camera is:
Answer: A — Inverted (upside down) and real
Because light rays from the top of the object travel straight to the bottom of the screen (and vice versa) through the small hole, the pinhole camera forms an inverted, real image.
Q15. hard
In a plane mirror, your right hand appears to be your left hand. This effect is called:
Answer: A — Lateral inversion
Lateral inversion is the left-right reversal seen in a mirror image. This is why the word 'AMBULANCE' is written reversed on the front of ambulances - so it reads correctly in a driver's rear-view mirror.
Q16. hard
The word 'AMBULANCE' is written in reverse on the front of an ambulance so that:
Answer: A — Drivers ahead can read it correctly in their rear-view mirror
Because a plane mirror laterally inverts an image, the reversed writing appears correct (AMBULANCE) when a driver ahead sees it in the rear-view mirror, prompting them to give way.
Q18. hard
A kaleidoscope produces beautiful changing patterns using:
Answer: A — Multiple reflections in mirrors set at an angle
A kaleidoscope uses two or three mirrors placed at an angle. Small coloured pieces reflect multiple times between the mirrors, creating symmetric, ever-changing patterns.
Q20. hard
Why can we see our clear reflection in still water but not in rippling water?
Answer: A — Still water is smooth and reflects light regularly; ripples scatter the light
A smooth water surface reflects light in an orderly way, forming a clear image. When the water ripples, the uneven surface scatters the reflected light, so the image breaks up.
Q24. hard
We are able to SEE an object because:
Answer: A — Light from the object enters our eyes
We see an object when light (either emitted by it or reflected from it) enters our eyes. Non-luminous objects are seen by the light they reflect. In complete darkness, we cannot see anything.
Q26. hard
During a solar eclipse, the shadow of which body falls on the Earth?
Answer: A — The Moon (it comes between the Sun and Earth)
A solar eclipse occurs when the Moon comes between the Sun and the Earth, so the Moon's shadow falls on part of the Earth, blocking sunlight there.
Q27. hard
During a lunar eclipse, the shadow of which body falls on the Moon?
Answer: A — The Earth
A lunar eclipse occurs when the Earth comes between the Sun and the Moon, so the Earth's shadow falls on the Moon, darkening it.
Q29. hard
A pencil half-dipped in a glass of water appears bent at the water surface. This is due to:
Answer: A — Refraction of light
Light from the submerged part of the pencil bends (refracts) as it moves from water to air, making the pencil appear bent or broken at the surface. The pencil itself is straight.
Q31. hard
A glass prism splits white light into its colours. This splitting is called:
Answer: A — Dispersion
Dispersion is the splitting of white light into its seven constituent colours (VIBGYOR) when it passes through a prism. A rainbow forms by the dispersion of sunlight by water droplets.
Q32. hard
A rainbow is formed by which processes acting on sunlight through water droplets?
Answer: A — Refraction, dispersion and reflection
A rainbow forms when sunlight enters tiny water droplets, refracts and disperses into seven colours, reflects inside the droplet, and refracts again on the way out - producing the coloured arc.
Q36. hard
The mirrors used as rear-view mirrors in vehicles (giving a wide view) are usually:
Answer: A — Convex mirrors
Convex mirrors curve outward and give a wider field of view (though the image is smaller). This makes them useful as rear-view (side) mirrors on vehicles to see more of the road behind.
Q37. hard
The concave mirror used by dentists and for shaving/make-up gives a:
Answer: A — Magnified (enlarged) image when the object is close
A concave mirror (curved inward) can produce an enlarged, upright image when the object is placed close to it - useful for shaving mirrors and by dentists to see teeth clearly.
Q40. hard
Two objects of the same size are placed at different distances from a light source. The one CLOSER to the light will cast a shadow that is:
Answer: A — Larger
An object closer to a light source blocks more of the spreading light, casting a larger shadow. The farther object casts a smaller shadow.
Q42. hard
In a pinhole camera, if the object is far away and the hole is small, the image on the screen is:
Answer: A — Sharp but inverted
A very small hole gives a sharper (but dimmer) inverted image, because each point of the object sends a thin, well-defined ray through the hole to the screen.
Q44. hard
A ray of light from a torch appears as a straight beam. This directly shows that light:
Answer: A — Travels in a straight line
The straight beam from a torch (visible in dusty air) demonstrates the rectilinear (straight-line) propagation of light.
Q46. hard
The image in a plane mirror is called 'virtual' because:
Answer: A — It appears behind the mirror and cannot be caught on a screen
A plane mirror's image seems to be behind the mirror and cannot be formed on a screen - such an image is called virtual. (A real image, like in a pinhole camera, CAN be caught on a screen.)
Q48. hard
Which statement about a shadow is TRUE?
Answer: A — A shadow is always on the opposite side of the object from the light source
A shadow always forms on the side of the object away from the light source, because the object blocks the straight-travelling light. Transparent objects do not form dark shadows.
Q50. hard
Which of these correctly classifies the materials?
Answer: A — Clear glass - transparent; Butter paper - translucent; Wood - opaque
Clear glass lets light through fully (transparent); butter paper lets some light through (translucent); wood blocks light completely (opaque).
Q52. hard
Why does a swimming pool look shallower than it actually is?
Answer: A — Because of the refraction (bending) of light at the water surface
Light from the bottom of the pool bends (refracts) as it leaves the water, making the bottom appear raised. So the pool looks shallower than its real depth - a refraction effect.
Q54. hard
Two plane mirrors placed parallel and facing each other produce:
Answer: A — Many images (multiple reflections)
When two mirrors face each other, light reflects back and forth between them repeatedly, producing a series of many images - an example of multiple reflection.
Q56. hard
Which statement is TRUE about the image formed by a plane mirror?
Answer: A — It is virtual, erect, same size, and laterally inverted
A plane mirror forms an image that is virtual (behind the mirror), erect (upright), the same size as the object, and laterally inverted (left-right swapped).
Q59. hard
When you look at yourself in a plane mirror and raise your RIGHT hand, the image raises its:
Answer: A — Left hand (due to lateral inversion)
Because of lateral inversion, the mirror swaps left and right. So when you raise your right hand, your mirror image appears to raise its left hand.