Light is a very complex phenomenon, but in many situations its behavior can be understood with a simple model based on rays and wave fronts. A ray is a thin beam of light that travels in a straight line. A wave front is the line (not necessarily straight) or surface connecting all the light that left a source at the same time. For a source like the Sun, rays radiate out in all directions; the wave fronts are spheres centered on the Sun. If the source is a long way away, the wave fronts can be treated as parallel lines.

The law of reflection

Objects can be seen by the light they emit, or, more often, by the light they reflect. Reflected light obeys the law of reflection, that the angle of reflection equals the angle of incidence.

 

mirror1Law of Reflection: In the diagram at left, a light ray PO strikes a vertical mirror at point O, and the reflected ray is OQ. By projecting an imaginary line through point O perpendicular to the mirror, known as the normal, we can measure the angle of incidenceθi and the angle of reflectionθr. The law of reflection states that θi = θr, or in other words, the angle of incidence equals the angle of reflection.

 Laws of reflection:

The laws of reflection are as follows:

  1. The incident ray, the reflected ray and the normal to the reflection surface at the point of the incidence lie in the same plane.
  2. The angle which the incident ray makes with the normal is equal to the angle which the reflected ray makes to the same normal.
  3. The reflected ray and the incident ray are on the opposite sides of the normal.

Ray optics:

Mirrors with curved surfaces can be modeled by ray tracing and using the law of reflection at each point on the surface. For mirrors with parabolic surfaces, parallel rays incident on the mirror produce reflected rays that converge at a common focus. Other curved surfaces may also focus light, but with aberrations due to the diverging shape causing the focus to be smeared out in space. In particular, spherical mirrors exhibit spherical aberration. Curved mirrors can form images with magnification greater than or less than one, and the image can be upright or inverted. An upright image formed by reflection in a mirror is always virtual, while an inverted image is real and can be projected onto a screen.

Grades  Activities & Simulations (click underlined simulations to view in below window)
4th - 8th Plain mirrors at angles – Multiple imagesLook into the mirror and trace the path,  Plane Mirror – Image characteristics, Ray diagram for Plane Mirror, What length of the mirror is required
8th-12th and above Build yourself – Ray diagram construction- Convex mirror, Convex mirror – Image characteristics, Convex mirror – Radius of curvature and f, Convex mirror -Size, focal length and Magnification, Build yourself- Ray diagram construction-Concave mirror, Concave Mirror – Image characteristics, Concave mirror -Size, focal length and Magnification, Concave mirror – Radius of curvature and f, Light-Total internal reflection and Fiber optics, Huygens principle – Wave fronts and Reflection, Diffused Reflection, Find the fastest Path, Plane Mirror – Image characteristics, Ray diagram for Plane Mirror, What length of the mirror is required, Plain mirrors at angles – Multiple imagesLook into the mirror and trace the path

 

Note – You can get all the above simulations, quizzes, activities by purchasing this App from the App store.

Click the above links to load the simulation in this window
Handpicked videos by expert teachers
You can click on the below list of images to learn more
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Concave mirror -Size, focal length and Magnification

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Concave mirror -Size, focal length and Magnification

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Simulation - Concave mirror -Size, focal length and Magnification
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Reflection – Fastest path of Light

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Reflection – Fastest path of Light

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Image of the interactive - Reflection:Fastest path of Light
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Huygen’s principle – Wavefronts and Reflection

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Huygen’s principle – Wavefronts and Reflection

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Image of the interactive - Huygens principle - Wavefronts and Reflection
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Total internal reflection and Fiber optics

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Total internal reflection and Fiber optics

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Image of the interactive -Total internal reflection and Fiber optics
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Concave mirror -Size, focal length and Magnification

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Concave mirror -Size, focal length and Magnification

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Image of the interactive -Concave mirror -Size, focal length and Magnification
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Ray diagram construction for Concave mirror

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Ray diagram construction for Concave mirror

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Image of the interactive -Ray diagram construction for Concave mirror
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Convex mirror Radius of curvature and f

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Convex mirror Radius of curvature and f

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Image of the interactive - Convex mirror - Radius of curvature and f
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Ray diagram construction for Convex mirror

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Ray diagram construction for Convex mirror

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Image of the interactive - Ray diagram construction- Convex mirror
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Length of the mirror to view full image

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Length of the mirror to view full image

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Image of the interactive - Length of the mirror to view full image