By tackling these Class 7 Science Extra Questions and Class 7 Curiosity Chapter 11 Extra Question Answer Light Shadows and Reflections, students will build a solid foundation in the topic.
Class 7 Science Chapter 11 Light Shadows and Reflections Extra Questions
Class 7 Science Chapter 11 Extra Questions on Light Shadows and Reflections
Light Shadows and Reflections Class 7 Very Short Question Answer
Question 1.
What is light?
Answer:
Light is form of energy, which makes objects visible.
Question 2.
Which kind of light source is sun?
Answer:
Sun is a natural and light emitting source.
Question 3.
Where does the moonlight come from?
Answer:
Moon reflects sun’s light. Itself does not emit light.
Question 4.
What are transparent objects?
Answer:
The objects through which light passes completely.
Question 5.
What are translucent objects?
Answer:
The objects through which light passes partially.
Question 6.
What are opaque objects?
Answer:
The objects which blocks light.
Question 7.
What is formed when any object comes in path of light?
Answer:
Shadow formed
Question 8.
Which colour is of shadow?
Answer:
Shadow is of black or grey colour.
Question 9.
What is called reflection?
Answer:
Returning back of light from any surface is called reflection.
Question 10.
Which kind of image is formed in mirror?
Answer:
Virtual, straight and laterally inverted.
Question 11.
What is pinhole camera?
Answer:
It is a device in which light travels through a small hole and forms inverted image.
Question 12.
Which object does not forms shadow?
Answer:
A transparent object does not form shadow.
Question 13.
Where is periscope used?
Answer:
To look outside of submarine and bunkers.
Question 14.
What is essential for shadow formation?
Answer:
Light source, a translucent object and a screen
Question 15.
Which type of length of shadow is seen during noon?
Answer:
Smallest
Light Shadows and Reflections Class 7 Short Question Answer
Question 1.
Which are the two main types of light?
Answer:
(i) Natural light Sun. shining of lightning etc.
(ii) Artificial light: Bulb, torch, LED etc.
Question 2.
How does travel of light is in straight path proven?
Answer:
Matchboxes are kept in a straight line after making holes. If we flash light on first hole. It will seen outside of the last hole, but if one box is removed, then light does not reach to last hole, it proves that light travels in a straight path.
Question 3.
What is the difference between transparent, translucent and opaque objects?
Answer:
Transparent-Allow complete light to pass through (e.g. glass).
Answer:
Returning back of light from any surface is called reflection.
Question 10.
Which kind of image is formed in mirror?
Answer:
Virtual, straight and laterally inverted.
Question 11.
What is pinhole camera?
Answer:
It is a device in which light travels through a small hole and forms inverted image.
Question 12.
Which object does not forms shadow?
Answer:
A transparent object does not form shadow.
Question 13.
Where is periscope used?
Answer:
To look outside of submarine and bunkers.
Question 14.
What is essential for shadow formation?
Answer:
Light source, a translucent object and a screen
Question 15.
Which type of length of shadow is seen during noon?
Answer:
Smallest
Light Shadows and Reflections Class 7 Long Question Answer
Question 1.
What is light? Write its characteristics.
Answer:
Light is a form of energy which makes objects visible. Its main characteristics are :
(a) It travels in linear path
(b) It can be reflected
(c) It can be refracted
(d) It can form shadow
(e) It have a very high speed (3 × 108 m/s).
Question 2.
What is shadow? Write conditions for its formation.
Answer:
When any opaque object blocks the path of light, then a dark black is formed which is called shadow.
Conditions of shadow formation
(a) Should have a source of light
(b) An opaque object
(c) A screen of surface, where shadow is seen.
Question 3.
Differentiate between transparent, translucent and opaque objects with suitable examples.
Answer:
| Type | Transit of light | Example |
| Transparent | Complete | Glass, water |
| Translucent | Partial | Butter paper,thin cloth |
| Opaque | None/Zero | Wood, wall |
Question 4.
Write characteristics of image in mirror.
Answer:
Image formed by plane mirror is :
(a) Equal in size with an object
(b) Virtual (Does not formed on screen)
(c) Seen upright
(d) Laterally inverted (Left-right changes)
(e) Distance behind mirror is equal to object.
Question 5.
What is pinhole camera? Explain its working process.
Answer:
A pinhole camera is a device in which the light rays from an object pass through a tiny hole (a pinhole) and form an image on screen. Principle : Light travels in a linear path. Working process : Ray emitted through hole from object make an inverted and real image on screen.
Question 6.
What is periscope? Write its formation and uses.
Answer:
Periscope is a device in which two plane mirrors are placed on angle of 45°. The ray coming from upper mirror reaches eye by reflecting through the lower mirror.
Uses : To watch surface of submarine. To watch backside of bunker or wall.
Question 7.
Should we use L.E.D.s? What are their benefits?
Answer:
Yes, we should use L.E.D.s. These are modern light sources that consume much less power, are brighter and last longer than traditional lamps. This not only reduces electricity bills but it also better for environment. Recognising their advantages the Indian government has made substantial efforts to promote the use of LED lamp nationwide. At their end of life, LED lamps must be appropriately disposed or recycled, and not thrown in garbage.
Question 8.
Explain formation of shadow.
Answer:
When an opaque object blocks light path, resulting, a dark shape or spot similar to that object formed on screen or the earth, which is called shadow. A shadow will only formed when three things are present-source of light, an opaque object and a screen on which the shadow is formed. Shadow helps us to understand properties of light in our daily life. It provides us informations about size, and form of an object and also about direction of light.
For example, as we are standing under sunlight, our shadow will be formed on the earth. As the position of the sun changes, length and direction of shadow will be changed.
Question 9.
Explain usefulness of transparent, translucent and opaque objects in science and daily life.
Answer:
Transparent: Glass of window, spectacles, lenses-Allow light to pass through.
Translucent: Screen, butter paper-Dim light appear used for privacy.
Opaque: Walls, woods-For shadow formation, and privacy.
Question 10.
Explain reflection of light by an activity.
Answer:
Find a shiny flat steel plate or a plane mirror, that is, a mirror that is flat and not curved. Take it outside and let the sunlight fall on the shiny surface. Turn the shiny plate or mirror in different directions to redirect the light onto a wall or nearby surface. Now, tilt the shiny plate or mirror in different ways and observe the light spot on the wall. Light always travels in straight lines and changes direction when it falls on the shiny plate or mirror changes the direction of light that falls upon it. This change in direction of light by a mirror is called reflection of light.
Question 11.
“Importance of light in our life.” Enlighten the subject.
Answer:
Light is an essential part of our lives. It helps us to visualise and also helps us to recognise objects clearly. Sunlight is the main source of light energy, life is not possible without it. Plants prepare food with the help of photosynthesis, which feeds entire animal kingdom. Difference of day and night is understood only with the help of light, which help to maintain balance between work and rest.
Reflection, refraction, shadow, mirror, camera etc. are based on principles of light. Moreover, light is used in medicine, communication, energy production, and in technical development. So, light is essential for life, nature and for progress.
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