Image Formation by Concave Mirrors

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Questions and Answers

What is the direction of the distance measured when a negative sign is used in the sign convention?

Parallel to the principal axis

In the direction of the incident ray

Perpendicular to the principal axis

Opposite to the direction of the incident ray (correct)

What is the focal length of a convex mirror according to the sign convention?

Zero

Positive

Negative (correct)

Infinity

What is the height of the image taken as for a real image?

Negative (correct)

Infinity

Positive

Zero

What is the purpose of the mirror formula in a convex mirror?

To find the position, nature, and size of the image Signup and view all the answers

What is the magnification of a spherical mirror represented by?

The letter m Signup and view all the answers

What is the radius of curvature of the convex mirror in the example given?

3m Signup and view all the answers

What is the purpose of using concave mirrors in solar furnaces?

To concentrate sunlight to produce heat Signup and view all the answers

What is shown in Fig. 5(a) and Fig. 5(b)?

Ray diagrams for a convex mirror Signup and view all the answers

What is the formula that relates the object distance, image distance, and focal length of a spherical mirror?

1/u - 1/v = 1/f Signup and view all the answers

According to the sign convention for reflection by spherical mirrors, where is the object always placed?

To the left of the mirror Signup and view all the answers

What can be said about the image formed by a convex mirror?

It is always virtual and upright Signup and view all the answers

What is the term for the distance of the principal focus from the pole of a spherical mirror?

Focal length Signup and view all the answers

Where is the principal focus of a spherical mirror located?

Midway between the pole P and center of curvature C Signup and view all the answers

What is the nature of the image formed by a concave mirror when the object is placed between the focal point and the mirror?

Virtual and upright Signup and view all the answers

What is the purpose of using concave mirrors in torches, search-lights, and vehicles headlights?

To get powerful parallel beams of light Signup and view all the answers

What determines the size of the image formed by a concave mirror?

The position of the object in relation to points P, F, and C Signup and view all the answers

What is the nature of the image formed by a concave mirror when the object is placed beyond the focal point of the mirror?

Real and inverted Signup and view all the answers

What is the purpose of using ray diagrams in mirror optics?

To show the path of light rays Signup and view all the answers

Study Notes

Sign Convention for Spherical Mirrors

Distances parallel to the principal axis are measured from the pole (P) of the mirror.
Negative sign indicates distance measured in the direction opposite to the incident ray, while positive sign indicates distance measured in the direction of the incident ray.
Distance below the axis is negative, while distance above is positive.
Focal length (f) is positive for a concave mirror and negative for a convex mirror.

Magnification of Spherical Mirrors

Magnification (m) is given by m = hi/uo = -ho/u, where hi is the height of the image and ho is the height of the object.
Height of the object is taken as positive, as it is usually placed above the principal axis.
Height of the image is taken as positive for virtual images and negative for real images.

Image Formation by Convex Mirrors

Image formation by a convex mirror can be understood through ray diagrams for two positions of the object: at infinity and at a finite distance from the mirror.
Results are summarized in Table 2, showing nature, position, and relative size of the image formed by a convex mirror.

Mirror Formula and Magnification

Mirror formula: 1/v + 1/u = 1/f, relating object distance (u), image distance (v), and focal length (f).
Formula is valid for all spherical mirrors and all positions of the object.

Image Formation by Concave Mirrors

Image formation by a concave mirror depends on the position of the object in relation to points P, F, and C.
Nature, position, and size of the image formed by a concave mirror vary depending on the object's position.
Image is real for some positions of the object and virtual for others.
Image is either magnified, reduced, or has the same size, depending on the object's position.

Uses of Concave Mirrors

Concave mirrors are used in torches, search-lights, and vehicles' headlights to produce powerful parallel beams of light.

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Description

Understand how concave mirrors form images and how the position of the object affects the nature, position, and size of the image. Learn to locate the image and determine if it's real or virtual.