Advertisements
Advertisements
प्रश्न
A 10 mm long awl pin is placed vertically in front of a concave mirror. A 5 mm long image of the awl pin is formed at 30 cm in front of the mirror. The focal length of this mirror is
विकल्प
–30 cm
–20 cm
–40 cm
–60 cm
उत्तर
–20 cm
Explanation -
`"m" = "h"^'/"h" = (-υ )/"u"` or
`"u" = ((-υ ) xx "h")/"h"^'`
`= (-(-30 "cm") xx (10 "mm"))/(-5 "mm") `
= -60 cm
∴ `1/"f" = 1/"u" + 1/υ`
= `-1/60 - 1/30`
= `-1/20` or f = -20 cm
APPEARS IN
संबंधित प्रश्न
Explain the difference between a plane mirror, a concave mirror, and a convex mirror with respect to the type and size of the images produced.
If an object is placed between two mirrors which are parallel to each other, the number of images formed is ______.
A child is standing in front of a magic mirror. She finds the image of her head bigger, the middle portion of her body of the same size and that of the legs smaller. The following is the order of combinations for the magic mirror from the top.
In which of the following, the image of an object placed at infinity will be highly diminished and point sized?
The ______ of a mirror determines the type of image it forms.
Curved mirrors form the perfect image of an object.
Curved mirrors produce images that are either enlarged or diminished.
Assertion: The mirrors used in searchlights are parabolic and not concave spherical.
Reason: In a concave spherical mirror the image formed is always virtual.
If two mirrors are placed at an inclination of 30° then how many images can be seen?
Visit a laughing gallery in some science centre, or a science park or a village mela. You will find some large mirrors there. You can see your distorted and funny images in these mirrors. Try to find out the kind of mirrors used there.
