A student has obtained an image of a well-illuminated distant object on a screen to determine the focal length, $F_{1}$ of the given spherical mirror. The teacher then gave him another mirror of focal length, $F_{2}$ and asked him to obtain a focused image of the same object on the same screen. The student found that in order to focus the same object using the second mirror, he has to move the mirror away from the screen. From this observation it may be concluded that both the spherical mirrors given to the student were (select the correct option)

Concave and

F_{1}

F_{2}

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Concave and

F_{1}

F_{2}

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Convex and

F_{1}

F_{2}

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Convex and

F_{1}

F_{2}

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Solution

The correct option is C Concave and $F_{1}$ < $F_{2}$
Both the mirrors have to be concave, as the light is converged and focused on the screen from a distant object. Also, Since the second mirror is moved further from the screen, it means it has a greater focal length than the first concave mirror. So, we can conclude that the mirror is concave and $F_{1}$ < $F_{2}$

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Similar questions

A student has obtained an image of a distant on a screen to determine the focal length $F_{1}$ of the given lens. His teacher, after checking the image, gave him another lens of focal length $F_{2}$ 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:

Q. A student has obtained an image of a distant object on a screen to determine the focal length

F_{1}

of the given lens. His teacher after checking the image, gave him another lens of focal length

F_{2}

and asked 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 :

Object Pin	Convex Lens	Convex Mirror	Image Pin
22.2 cm	32.2 cm	45.8 cm	71.2 cm

To find the focal length of a convex mirror, a student records the following data:
The focal length of the convex lens is

f_{1}

and that of mirror is

f_{2}

. Then taking index correction to be negligibly small,

f_{1}

and

f_{2}

are close to :

Q. A student has to determine the focal length of a concave mirror by obtaining the image of a distant object on a screen. For getting best result he should focus:

To determine focal length of a concave mirror a student obtains the image of a well lit distant object on a screen. To determine the focal length of the given concave mirror he needs to measures the distance between:

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