Images - Section 36.1 - Mirrors and Lenses

Oct 25, 2026

Covers the formation and identification of images produced by mirrors and lenses, focusing on object distance (p), image distance (q), and lateral magnification (M). Explains how images are located by extending diverging rays to their intersection point and distinguishes real images (light actually passes and diverges) from virtual images (light only appears to diverge). Special attention is given to flat mirrors, including why they always form virtual images, basic geometric construction, and the rule that |p| = |q|. Also derives magnification concepts and orientation.

LanguageEnglish

CategoryTechnology

FormatPDF

Pages108

Reading Time4 h 32 min

AccessFree to download

Images

Notation for Mirrors and Lenses

Images Formed by Flat Mirrors

Lateral Magnification

34-36. Images Image of Formation Images can result when light rays encounter flat or curved surfaces between two media. Images can be formed either by reflection or refraction due to these surfaces. Mirrors and lenses can be designed to form images with desired characteristics. Introduction Notation for Mirrors and Lenses The object distance is the distance from the object to the mirror or lens. ▪ Denoted by p The image distance is the distance from the image to the mirror or lens. ▪ Denoted by q The lateral magnification of the mirror or lens is the ratio of the image height to the object height. ▪ Denoted by M Section 36.1 Images Images are always located by extending diverging rays back to a point at which they intersect. Images are located either at a point from which the rays of light actually diverge or at a point from which they appear to diverge. A real image is formed when light rays pass through and diverge from the image point. ▪ Real images can be displayed on screens. A virtual image is formed when light rays do not pass through the image point but only appear to diverge from that point. ▪ Virtual images cannot be displayed on screens. Section 36.1 Images Formed by Flat Mirrors Simplest possible mirror Light rays leave the source and are reflected from the mirror. Point I is called the image of the object at point O. The image is virtual . No light ray from the object can exist behind the mirror, so the light rays in front of the mirror only seem to be diverging from I. Section 36.1 Images Formed by Flat Mirrors, cont. A flat mirror always produces a virtual image. Geometry can be used to determine the properties of the image. There are an infinite number of choices of direction in which light rays could leave each point on the object. Two rays are needed to determine where an image is formed. Section 36.1 Images Formed by Flat Mirrors, Geometry One ray starts at point P, travels to Q and reflects back on itself. Another ray follows the path PR and reflects according to the law of reflection. The triangles PQR and P’QR are congruent. Section 36.1 Images Formed by Flat Mirrors, final To observe the image, the observer would trace back the two reflected rays to P’. Point P’ is the point where the rays appear to have originated. The image formed by an object placed in front ofa flat mirror is as far behind the mirror as the object is in front of the mirror. ▪ |p| = |q| Section 36.1 Lateral Magnification Lateral magnification, M, is defined as M 􀁻 Image height = h ' Object height h ▪ This is the lateral magnification for any type of mirror. ▪ It is also valid for images formed by lenses. ▪ Magnification does not always mean bigger, the size can either increase or decrease. ▪ M can be less than or greater than 1. Section 36.1 Lateral Magnification of a Flat Mirror The lateral magnification of a flat mirror is +1. This means that h’ = h for all images. The positive sign indicates the object is upright. ▪ Same orientation as the object Section 36.1

FAQs

What do p and q represent for mirrors and lenses?

The object distance is p, measured from the object to the mirror or lens. The image distance is q, measured from the image to the mirror or lens.

How are images located using light rays?

Images are always located by extending diverging rays back to the point where they appear to intersect.

Why does a flat mirror always produce a virtual image?

No light ray from the object exists behind the mirror; rays in front only seem to diverge from the image point. Therefore the image is virtual and cannot be displayed on a screen.

Oct 25, 2026

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