A concave mirror of focal length 10 cm forms an image which is double the size of object when the object is placed at two different positions. The distance between the two positions of the object is cm.
Ray Optics and Optical Instruments
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A rod of length 10 cm lies along the principal axis of a concave mirror of focal length 10 cm as shown in figure. The length of the image is cm. [figure]
- 2.5
- 5
- 7.5
- 7
Distance between an object and three times magnified real image is 40 cm. The focal length of the mirror used is cm.
- -20
- -15/2
- -10
- -15
A mirror is used to produce an image with magnification of 14. If the distance between object and its image is 40 cm, then the focal length of the mirror is .
- 10 cm
- 12.7 cm
- 10.7 cm
- 15 cm
When an object is placed 40 cm away from a spherical mirror an image of magnification 12 is produced. To obtain an image with magnification of 13, the object is to be moved :
- 20 cm away from the mirror.
- 20 cm towards the mirror.
- 80 cm away from the mirror.
- 40 cm away from the mirror.
Distance between object and its image (magnified by - 13) is 30 cm. The focal length of the mirror used is ( x4 )cm, where magnitude of value of x is .
A finite size object is placed normal to the principal axis at a distance of 30 cm from a convex mirror of focal length 30 cm. A plane mirror is now placed in such a way that the image produced by both the mirrors coincide with each other. The distance between the two mirrors is :
- 45 cm
- 15 cm
- 22.5 cm
- 7.5 cm
Two identical objects are placed in front of convex mirror and concave mirror having same radii of curvature of 12 cm, at same distance of 18 cm from the respective mirrors. The ratio of sizes of the images formed by convex mirror and by concave mirror is :
- 2
- 1/2
- 1/3
- 3
A concave mirror produces an image of an object such that the distance between the object and image is 20 cm. If the magnification of the image is -3, then the magnitude of the radius of curvature of the mirror is :
- 3.75 cm
- 15 cm
- 7.5 cm
- 30 cm