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Questions
What is the magnification of the images formed by plane mirrors and why?
The magnification produced by a plane mirror is +1. What does this mean?
Solution
As m = `(h_2)/(h_1) = +1`
h2 = h1
i.e., the size of the image is equal to the size of the object. Further, the + sign of m indicates that the image is erect and hence virtual..
RELATED QUESTIONS
Which type of mirror could be used as a dentist's mirror?
The image formed by a concave mirror is virtual, erect and magnified. The position of object is:
(a) at focus
(b) between focus and centre of curvature
(c) at pole
(d) between pole and focus
A virtual, erect and magnified image of an object is to be produced with a concave mirror of focal length 12 cm. Which of the following object distance should be chosen for this purpose?
(i) 10 cm
(ii) 15 cm
(iii) 20 cm
Give reason for your choi
What sign (+ve or −ve) has been given to the following on the basis of Cartesian Sigh Convention?
Height of a virtual image.
Fill in the following blank with suitable word:
If the magnification has a plus sign, than image is ......... and.........
Fill in the following blank with suitable word:
If the magnification has a minus sign, than the image is ......... and .......
A dentist's mirror has a radius of curvature of 3 cm. How far must it be placed from a small dental cavity to give a virtual image of the cavity that is magnified five times?
When an object is placed at a distance of 36 cm from a convex lens, an image of the same size as the object is formed. What will be the nature of image formed when the object is placed at a distance of:
20 cm from the lens?
What is the nature of the image formed by a convex lens if the magnification produced by the lens is +3?
What is the nature of the image formed by a convex lens if the magnification produced by the lens is, – 0.5?
At what distance should an object be placed from a convex lens of focal length 18 cm to obtain an image at 24 cm from it on the other side? What will be the magnification produced in this case?
The filament of a lamp is 80 cm from a screen and a converging lens forms an image of it on a screen, magnified three times. Find the distance of the lens from the filament and the focal length of the lens.
Determine how far an object must be placed in front of a converging lens of focal length 10 cm in order to produce an erect (upright) image of linear magnification 4.
Linear magnification produced by a convex lens can be:
(a) less than 1 or more than 1
(b) less than 1 or equal to 1
(c) more than 1 or equal to 1
(d) less than 1, equal to 1 or more than 1
Magnification produced by a concave lens is always:
(a) more than 1
(b) equal to 1
(c) less than 1
(d) more than 1 or less than 1
If a magnification of, –1 is to be obtained by using a converging lens of focal length 12 cm, then the object must be placed:
(a) within 12 cm
(b) at 24 cm
(c) at 6 cm
(d) beyond 24 cm
A magnifying lens has a focal length of 100 mm. An object whose size is 16 mm is placed at some distance from the lens so that an image is formed at a distance of 25 cm in front of the lens.
Where should the object be placed if the image is to form at infinity?
A convex mirror has a focal length of 18 cm. The image of an object kept in front of the mirror is half the height of the object. What is the distance of the object from the mirror?
An object of height 7 cm is kept at a distance of 25 cm in front of a concave mirror. The focal length of the mirror is 15 cm. At what distance from the mirror should a screen be kept so as to get a clear image? What will be the size and nature of the image?
Assertion: The focal length of the mirror is /and the distance of the object from the focus is V then the magnification of the mirror will be `("f"/"f−u")`
Reason: Magnification = `"image distance"/ "object distance"` = `(-"v"/"u")`
