Advertisements
Advertisements
प्रश्न
A small object is so placed in front of a convex lens of 5 cm focal length that a virtual image is formed at a distance of 25 cm. Find the magnification.
उत्तर
Given:
Focal length, f = 5 cm
Image distance, v =-25 cm (Image is virtual.)
Applying the lens formula, we get:
1/v -1/u = 1/f (u = Object distance)
1/(-25) -1/u = 1/5
or, 1/u =1/(-25)-1/5
or, 1/u =-6/25
or,
u = -25/6 cm
Now,
Magnification, m = v/u
= (-25)/(-25/6)
= +6
APPEARS IN
संबंधित प्रश्न
Which type of mirror could be used as a dentist's mirror?
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.
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:
10 cm from the lens?
Write down the magnification formula for a lens in terms of object distance and image distance. How does this magnification formula for a lens differ from the corresponding formula for a mirror?
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.
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
What is the nature of the image formed by a concave mirror if the magnification produced by the mirror is +4?
