Sign Conventions

Concept Explanation

Sign Conventions

Sign Convention:

With spherical mirrors, we generally come across four distances parallel to and two distances perpendicular to the principal axis. Each of these six distances has a particular mathematical quantity associated with it. These quantities are given in table.

Distance	Quantity	Symbol
From the pole to the object	object-distance	$large u$
From the pole to the image	image-distance	$large v$
From the pole to the focus	focal length	$large f$
From the pole to the centre	radius of curvature	$large r$
Height of the object	object-height	$large h_{o}$
Height of the image	image-height	$large h_{e}$

The above definitions of u and v are for a point object placed on the principal axis. If an object is placed away from the principal axis, u corresponds to the distance from the pole to the foot of the perpendicular drawn from the object to the principal axis. Similarly, v corresponds to the distance from the pole to the foot of the perpendicular drawn from the image to the principal axis. The quantities $large h_{o}$ and $large h_{e}$ are defined for a linear, extended object placed perpendicular to the principal axis.

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Sample Questions

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Question : 1

Which of the following are correct ? (a) The quantities $large h_{o}$ and $large h_{e}$ are defined only or a linear, extended object placed parallel to the principal axis. (b) If an object is placed away from the principal axis, v corresponds to the distance from the pole to the foot of the perpendicular drawn from the image to the principal axis.
A. Only (a) is correct .	B. Only (b) is correct .	C. Both (a) and (b) is correct .	D. None of these .
Right Option : B
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Question : 2

Which of the following are correct ? (a) When object-height $large h_{o}$ is positive and the image-height $large h_{e}$ is negative we can say that the image is formed is inverted (b) When object-height $large h_{o}$ is less that the image-height $large h_{e}$ we can say that the image is formed is magnified. (c) When object-height $large h_{o}$ and the image-height $large h_{e}$ are both positive we can say that the image is formed is erect.
A. Only (a) and (b) is correct .		B. Only (b) and (c) is correct .
C. Only (a) and (c) is correct .		D. All of these .
Right Option : D
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Question : 3

Which of the following are correct ? (a) When object-height $large h_{o}$ is positive and the image-height $large h_{e}$ is positive and are of equal value we can say that the image is formed is inverted (b) When object-height $large h_{o}$ is more that the image-height $large h_{e}$ and both are positive we can say that the image is formed is erect and diminished.
A. Only (a) is correct .		B. Only (b) is correct .
C. Both (a) and (b) is correct .		D. None of these .
Right Option : A
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Sign Conventions

Sign Conventions

Sign Convention:

Students / Parents Reviews [10]

Manish Kumar

Hiya Gupta

Shivam Rana

Aman Kumar Shrivastava

Shreya Shrivastava

Eshan Arora

Om Umang

Cheshta

Yatharthi Sharma

Prisha Gupta