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प्रश्न
With the help of an appropriate ray diagram, state the sign conventions for reflection by a spherical mirror.
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उत्तर
The sign convention for reflection by spherical mirrors is as follows:-
- The object is always placed to the left of the mirror.
- All distances parallel to the principal axis are measured from the pole of the mirror.
- All the distances measured to the right of the origin are taken as positive, while those measured to the left of the origin are taken as negative.
- Distances measured perpendicular to and above the principal axis are taken as positive.
- Distances measured perpendicular to and below the principal axis are taken as negative.
- The focal length of a convex mirror is positive, while that of a concave mirror is negative.
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संबंधित प्रश्न
List four specific characteristics of the images of the objects formed by convex mirrors.
To construct ray diagrams, two rays of light are generally so chosen that it is easy to determine their directions after reflection from a mirror. Choose two such rays and state the path/direction of these rays after reflection from a concave mirror. Use these two rays to find the position and nature of the image of an object placed at a distance of 8 cm from a concave mirror of focal length 12 cm.
A student wants to project the image of a candle flame on the walls of the school laboratory by using a mirror.
(a) Which type of mirror should he use and why?
(b) At what distance, in terms of focal length 'f' of the mirror, should he place the candle flame to get the magnified image on the wall?
(c) Draw a ray diagram to show the formation of the image in this case.
(d) Can he use this mirror to project a diminished image of the candle flame on the same wall? State 'how' if your answer is 'yes' and 'why not' if your answer is 'no.'
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.
A ray of light is incident on a plane mirror making an angle of 90° with the mirror surface. The angle of reflection for this ray of light will be:
(a) 45°
(b) 90°
(c) 0°
(d) 60°
Draw the following diagram in your answer book and show the formation of image of the object AB with the help of suitable rays:
According to the "New Cartesian Singh Convention" for mirrors, what sign has been given to the focal length of:
a convex 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
An object is placed at a distance of 10 cm from a concave mirror of focal length 20 cm.
Calculate the image distance.
A concave mirror produces a real image 1 cm tall of an object 2.5 mm tall placed 5 cm from the mirror. Find the position of the image and the focal length of the mirror.
A man holds a spherical shaving mirror of radius of curvature 60 cm, and focal length 30 cm, at a distance of 15 cm, from his nose. Find the position of image, and calculate the magnification.
A concave mirror cannot be used as:
(a) a magnifying mirror
(b) a torch reflector
(c) a dentist's mirror
(d) a real view mirror
Name the mirror(s) that can give (i) an erect and enlarged image, (ii) same sized, inverted image
Which of the following ray diagrams is correct for the ray of light incident on a concave mirror as shown in figure?
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| A | B | C | D |
In which of the following, the image of an object placed at infinity will be highly diminished and point sized?
A concave mirror of radius 30 cm is placed in water. It’s focal length in air and water differ by ______.
While looking at the above diagram, Nalini concluded the following.
- the image of the object will be a virtual one.
- the reflected ray will travel along the same path as the incident ray but in opposite direction.
- the image of the object will be inverted.
- this is a concave mirror and hence the focal length will be negative.
Which one of the above statements are correct?
The image formed by a concave mirror is real, inverted and of the same size as that of the object, the position of the object should be ______.
Between which two points of a concave mirror should an object be placed to obtain a magnification of -2?
Which type of mirror is used in the following?
Shaving mirror
