Advertisements
Advertisements
प्रश्न
If an object of 10 cm height is placed at a distance of 36 cm from a concave mirror of focal length 12 cm, find the position, nature and height of the image.
उत्तर
Distance of the object from the mirror 'u' = −36 cm
Height of the object 'ho'​ = 10 cm
Focal length of the mirror 'f' = −12 cm
We have to find the distance of the image 'v'.
Height of the image hi = ?
Using the mirror formula, we get
`1/f=1/v+1/u`
`1/-12=1/v+1/(-36)`
`1/v=1/36-1/12`
`1/v=(1-3)/36=-2/36`
v=-18cm
Distance of the image 'v' = −18 cm
Using the magnification formula, we get
`m=h_i/h_o=-v/u`
`h_i/10=(-(-18))/-36=-1/2`
`h_i=-1/2`
`h_i=-1/2`
`h_i=-5cm`
Height of the image 'hi'​ = −5 cm
Again using the magnification formula, we get​
`m=-v/v=(-(-18))/36`
m=-1/2
Thus, the image is real, inverted and small in size.
APPEARS IN
संबंधित प्रश्न
Study the following diagram and select the correct statement about the device 'X' :
(A) Device 'X' is a concave mirror of radius of curvature 12 cm
(B) Device 'X' is a concave mirror of focal length 6 cm
(C) Device 'X' is a concave mirror of focal length 12 cm
(D) Device 'X' is a convex of mirror of focal length 12 cm
In the concave reflector of a torch, the bulb is placed:
(a) between the pole and focus of reflector
(b) at the focus of reflector
(c) between focus and centre of curvature of reflector
(d) at the centre of curvature of reflector
An object is 100 mm in front of a concave mirror which produces an upright (erect image). The radius of curvature of the mirror is ______.
Giving reasons, state the 'signs' (positive or negative) which can be given to the following:
(a) object distance (u) for a concave mirror or convex mirror
(b) image distance (v) for a concave mirror
(c) image distance (v) for a convex mirror
What would your image look like if you stood close to a large:
concave mirror?
The diagram shows a dish antenna which is used to receive television signals from a satellite. The antenna (signal detector) is fixed in front of the curved dish.
Figure
(a) What is the purpose of the dish?
(b) Should it be concave or convex?
(c) Where should the antenna be positioned to receive the strongest possible signals?
(d) Explain what change you would expect in the signals if a larger dish was used.
State two uses of a concave mirror.
Under which of the following conditions a concave mirror can form an image larger than the actual object?
An image formed by a lens is erect. Such an image could be formed by a
