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प्रश्न
The radius of curvature of a spherical mirror is 20 cm. What is its focal length?
उत्तर
Radius of curvature, R = 20 cm
Focal length (f) = `R/2`
f = `R/2`
f = `20/2`
f = 10 cm
Hence, the focal length of the given spherical mirror is 10 cm.
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संबंधित प्रश्न
Draw a ray diagram to show the path of the refracted ray in each of the following cases:-
A ray of light incident on a concave lens is
(i) passing through its optical centre.
(ii) parallel to its principal axis.
(iii) directed towards its principal focus.
State two positions in which a concave mirror produces a magnified image of a given object. List two differences between the two images.
The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should be the position of the object?
With the help of a ray diagram, determine the position, nature and size of the image formed of an object placed at the centre of curvature of a concave mirror.
Make labelled ray diagrams to illustrate the formation of:
a real image by a converging mirror.
According to the "New Cartesian Singh Convention" for mirrors, what sign has been given to the focal length of:
a convex mirror?
A large concave mirror has a radius of curvature of 1.5 m. A person stands 10 m in front of the mirror. Where is the person's image?
Between which two points of concave mirror should an object be placed to obtain a magnification of:
(a) −3
(b) +25
(c) −0.4
What type of mirror should be used as a shaving mirror?
A concave mirror cannot be used as:
(a) a magnifying mirror
(b) a torch reflector
(c) a dentist's mirror
(d) a real view mirror
A convex mirror is used as a shaving mirror.
Radius of curvature of a spherical mirror is ............. its focal length.
State two uses of a concave mirror.
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 |
The radius of curvature of a concave mirror whose focal length is 5cm is ______
Pick out the concave and convex mirrors from the following and tabulate them.
Rear-view mirror, Dentist’s mirror, Torchlight mirror, Mirrors in shopping malls, Make-up mirror.
Rays from Sun converge at a point 15 cm in front of a concave mirror. Where should an object be placed so that size of its image is equal to the size of the object?
In which of the following, the image of an object placed at infinity will be highly diminished and point sized?
What is a concave and convex mirror?
Write the uses of the concave mirror.
