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. - Science

Advertisements
Advertisements

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.

Advertisements

Solution

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.

  Is there an error in this question or solution?
2015-2016 (March) All India Set 3

Video TutorialsVIEW ALL [1]

RELATED QUESTIONS

A student is using a convex lens of focal length 10 cm to study the image formation by a convex lens for the various positions of the object. In one of his observations, he may observe that when the object is placed at a distance of 20 cm from the lens, its image is formed at (select the correct option)

(A) 20 cm on the other side of the lens and is of the same size, real and erect.

(B) 40 cm on the other side of the lens and is magnified, real and inverted.

(C) 20 cm on the other side of the lens and is of the same size, real and inverted.

(D) 20 cm on the other side of the lens and is of the same size, virtual and erect.


The image of a candle flame placed at a distance of 30 cm from a spherical lens is formed on a screen placed on the other side of the lens at a distance of 60 cm from the optical centre of the lens. Identify the type of lens and calculate its focal length. If the height of the flame is 3 cm, find the height of its image.


At what distance from a concave lens of focal length 20 cm, should a 6 cm tall object be placed so that it forms an image at 15 cm from the lens ? Also determine the size of the image formed.


A student has obtained an image of a distant object on a screen to determine the focal length F1 of the given lens. His teacher, after checking the image, gave him another lens of  focal length F2 and asked him to focus the same object on the same screen. The student found that to obtain a sharp image, he has to move the lens away from the screen. From this finding, we may conclude that both the lenses given to the student were :

(A) Concave and F1 < F2

(B) Convex and F1 < F2

(C) Convex and F1 > F2

(D) Concave and F1 > F2


An object is held 20 cm away from a converging lens of focal length 10 cm. Find the position of the image formed.


The image seen in a plane mirror cannot be formed on a screen. What name is given to this type of image?


What is the difference between a real image and a virtual image? Give one example of each type of image


Linear magnification produced by a concave mirror may be:

(a) less than 1 or equal to 1
(b) more than 1 or equal than 1
(c) less than 1, more than 1 or equal to 1
(d) less than 1 or more than 1


If a magnification of, −1 (minus one) is to be obtained by using a converging mirror, then the object has to be placed:

(a) between pole and focus
(b) at the centre of curvature
(c) beyond the centre of curvature
(d) at infinity


A student wants to project the image of a candle flame on a screen 80 cm in front of a mirror by keeping the candle flame at a distance of 20 cm from its pole.

(i) Which type of mirror should the student use?

(ii) Find the magnification of the image produced.

(iii) Find the distance between the object and its image.

(iv) Draw a ray diagram to show the image formation in this case and mark the distance between the object and its image.


The image of a candle flame placed at a distance 30 cm from a spherical lens is formed on a screen placed at a distance of 60 cm from the lens. Identify the type of lens and calculate its focal length. If the height of the flame is 2.4 cm, find the height of its image.


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.


Give scientific reason.

Simple microscope is used for watch repairs.


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.


Solve the following example.

An object kept 60 cm from a lens gives a virtual image 20 cm in front of the lens. What is the focal length of the lens? Is it a converging lens or diverging lens?


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.


The lens of the eye is flattened when looking at nearby objects.


An object is placed vertically at a distance of 20 cm from a convex lens. If the height of the object is 5 cm and the focal length of the lens is 10 cm, what will be the position, size and nature of the image? How much bigger as compared to the object?


Magnification of a convex lens is


Share
Notifications



      Forgot password?
Use app×