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प्रश्न
In which equipment/s do you find ___________________
उत्तर
(i) Concave mirror is found in torches, headlights, flood lights, solar devices,dentist's mirror.
(ii) Convex lens is used in simple microscope, compound microscope, telescopes, optical instruments and spectacles.
(iii) Reflecting mirrors are used in projector lamps, telescopes.
APPEARS IN
संबंधित प्रश्न
State two positions in which a concave mirror produces a magnified image of a given object. List two differences between the two images.
The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should the position of the object be relative to the mirror? Draw ray diagram to justify your answer.
A concave mirror produces three times magnified (enlarged) real image of object placed at 10 cm in front of it. Where is the image located?
The image of a candle flame placed at a distance of 30 cm from a mirror is formed on a screen placed in front of the mirror at a distance of 60 cm from its pole. What is the nature of the mirror? Find its focal length. If the height of the flame is 2.4 cm, find the height of its image. State whether the image formed is erect or inverted
Fill in the following blank with suitable word:
The focal length of a concave mirror is the distance from the ......... to the mirror.
ill in the following blank with suitable word:
For a convex mirror, parallel rays of light appear to diverge from a point called the ......... .
Define (i) principal focus of a concave mirror, and (ii) focal length of a concave mirror.
For what position of an object, a concave mirror forms a real image equal in size to the object?
Explain why, a ray of light passing through the centre of curvature of a concave mirror gets reflected back along the same path.
Described with the help of a diagram, the nature, size and position of the image formed when an object is placed beyond the centre of curvature of a concave mirror.
Which mirror is used as a torch reflector? Draw a labelled diagram to show how a torch reflector can be used to produce a parallel beam of light. Where is the bulb placed in relation to the torch reflector?
State where an object must be placed so that the image formed by a concave mirror is:
(b) at infinity.
(c) the same size as the object.
According to the "New Cartesian Singh Convention" for mirrors, what sign has been given to the focal length of:
a concave mirror?
One of the following does not apply to a concave mirror this is:
(a) focal length is negative
(b) image distance can be positive or negative
(c) image distance is always positive
(d) height of image can be positive or negative
What is the position of the image when an object is placed at a distance of 20 cm from a concave mirror of focal length 20 cm?
An object is placed at a distance of 10 cm from a concave mirror of focal length 20 cm.
State two characteristics of the image formed.
A concave mirror produces three times enlarged virtual image of an object placed at 10 cm in front of it. Calculate the radius of curvature of the mirror.
An object is placed just outside the principal focus of concave mirror. Draw a ray diagram to show how the image is formed, and describe its size, position and nature.
What would your image look like if you stood close to a large:
concave mirror?
Which of the following are concave mirrors and which convex mirrors?
The mirror used by a dentist to examine the teeth of a person is:
(d) any one of the above
(a) convex
(b) concave
(c) plane
(d) any one of the above
The mirror which can form a magnified image of an object is:
(a) convex mirror
(b) plane mirror
(c) concave mirror
(d) both convex and concave mirror
A real image of an object is to be obtained. The mirror required for this purpose is:
(a) convex
(b) concave
(c) plane
(d) either convex or concave
Draw and complete the following diagrams to show what happens to the beams of light as they enter the glass block and then leave it:
Name the lens which can concentrate sun's rays to a point and burn a hole in a piece of paper.
Why are concave mirrors used in solar devices?
Answer the following question:
An object is placed at a distance of 30 cm from a concave lens of focal length 30 cm.
(i) Use the lens formula to determine the distance of the image from the lens.
(ii) List four characteristics of the image (nature, position, size, erect/inverted) in this case.
(iii) Draw a labelled diagram to justify your answer of the part (ii)
The radius of curvature of a concave mirror whose focal length is 5cm is ______
Large ______ mirrors are used to concentrate sunlight to produce heat in solar furnaces.
Under which of the following conditions a concave mirror can form an image larger than the actual object?
Rays from Sun converge at a point 15 cm in front of a concave mirror. Where should an object be placed so that size of its image is equal to the size of the object?
A concave mirror of radius 30 cm is placed in water. It’s focal length in air and water differ by ______.
Identify the device used as a spherical mirror or lens in following case, when the image formed is virtual and erect in case.
Object is placed between device and its focus, image formed is enlarged and behind it.
You are provided with a concave mirror, a convex mirror, a concave lens and a convex lens. To obtain an enlarged image of an object you can use either
An erect and enlarged image can be formed by
______ mirrors make things look larger when objects are placed close to them.
In torches, searchlights, and headlights of vehicles, the bulb is placed ______ of the concave mirror.
A student took three concave mirrors of different focal lengths and performed the experiment to see the image formation by placing an object at different distance with these mirrors as shown in the following table.
| Case No. | Object-distance | Focal length |
| I | 45 cm | 20 cm |
| II | 30 cm | 15 cm |
| III | 20 cm | 30 cm |
Now answer the following questions:
(a) List two properties of the image formed in Case I.
(b) In which one of the cases given in the table, the mirror will form real image of same size and why?
(c) Name the type of mirror used by dentists. Given reason why do they use such type of mirrors.
OR
(c) Look at the table and identify the situation (object distance and focal length) which resembles the situation in which concave mirrors are used as shaving mirrors? Draw a ray diagram to show the image formation in this case.
Which type of mirror is used in the following?
Floodlights
