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प्रश्न
What kind of mirror can have a focal length of, −20 cm?
उत्तर
A concave mirror can have a focal length of -20 cm. The reason being, a concave mirror has a negative focal length(according to the 'new cartesian sign convention').
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संबंधित प्रश्न
List four characteristics of the images formed by plane mirrors.
If an object is placed at a distance of 8 cm from a concave mirror of focal length 10 cm, discuss the nature of the image formed by drawing the ray diagram.
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
A converging mirror forms a real image of height 4 cm of an object of height 1 cm placed 20 cm away from the mirror:
- Calculate the image distance.
- What is the focal length of the mirror?
Choose the correct option from given alternative:
Consider the following properties of virtual images:
(A) cannot be projected on the screen
(B) are formed by both concave and convex lens
(C) are always erect
(D) are always inverted
Match the following.
| Convex mirror | Radio telescopes |
| Parobolic mirror | Rear – view mirror |
| Snell’s law | Kaleidoscope |
| Dispersion of light | sin i/sin r =μ |
| Refractive index | Rainbow |
Give any two applications of a concave and convex mirror.
A concave mirror of focal length 20 cm forms an image having twice the size of object. For the virtual position of object, the position of object will be at ______.
Between which two points of a concave mirror should an object be placed to obtain a magnification of -2?
