Advertisements
Advertisements
प्रश्न
The image formed by a spherical mirror is real, inverted and is of magnification -2. If the image is at a distance of 30 cm from the mirror, where is the object placed? Find the focal length of the mirror. List two characteristics of the image formed if the object is moved 10 cm towards the mirror.
उत्तर
Given: Magnification, m = -2
Distance of the image, v = -30 cm
Magnification, `m=-v/u`
∴`u=-v/m=-((-30))/((-2))`
∴u = -15 cm
Substituting these values in the mirror formula
`1/f=1/v+1/u`
=`1/((-30))+1/((-15))`
`1/f=-1/10`
∴f = 10 cm
When the object is moved 10 cm towards the mirror the new position of the object is
u' = -(15-10) = 5 cm
Substituting the new value in the mirror formula
`1/f=1/v+1/u`
`1/v^'=1/f-1/u=1/10-1/((-5))`
`1/v^'=1/10`
∴v' = 10 cm
Thus, the image is located 10 cm behind the mirror.
And magnification,`m'=(v')/(u')=-10/((-5))`
m' = 2
Since magnification is positive the image is erect and virtual.
Thus, the image is erect,virtual and magnified in nature.
APPEARS IN
संबंधित प्रश्न
In order to obtain a magnification of, −1.5 with a concave mirror of focal length 16 cm, the object will have to be placed at a distance
(a) between 6 cm and 16 cm
(b) between 32 cm and 16 cm
(c) between 48 cm and 32 cm
(d) beyond 64 cm
The lens A produces a magnification of, − 0.6 whereas lens B produces a magnification of + 0.6.
What is the nature of lens B?
At which position will you keep an object in front of a convex lens so as to get a real image of the same size as the object? Draw a figure.
Solve the following example.
5 cm high object is placed at a distance of 25 cm from a converging lens of focal length of 10 cm. Determine the position, size and type of the image.
At which position will you keep an object in front of convex lens to get a real image smaller than the object? Draw a figure.
What do you understand by the term magnification?
Find the position and magnification of the image of an object placed at distance of 8.0 cm in front of a convex lens of focal length 10.0 cm. Is the image erect or inverted?
Magnification of a convex lens is
The image of a candle flame formed by a lens is obtained on a screen placed on the other side of the lens. If the image is three times the size of the flame and the distance between lens and image is 80 cm, at what distance should the candle be placed from the lens? What is the nature of the image at a distance of 80 cm and the lens?
The magnification produced when an object is placed at a distance of 20 cm from a spherical mirror is +1/2. Where should the object be placed to reduce the magnification to +1/3.
