Ray Diagrams

Ray diagrams are graphical tools used to determine the location, size, orientation, and type of image formed by lenses and mirrors. They are based on the principles of geometric optics and use rays of light to trace the path of light as it interacts with optical elements like lenses and mirrors.

Interactive Ray Diagram

The following interactive ray diagram is a dynamic tool used to visualize how light rays interact with convex lens. It allows you to change the object’s position & height, focal point of the lens and observe real-time changes in the image formation.

Place the Object at Different Positions:
Beyond 2F: The image is real, inverted, and smaller.
At 2F: The image is real, inverted, and the same size.
Between F and 2F: The image is real, inverted, and larger.
At F: No image is formed (rays are parallel).
Inside F: The image is virtual, upright, and larger.

Observe the Rays:
A ray parallel to the principal axis refracts through the focal point.
A ray through the optical center continues straight.
A ray through the focal point refracts parallel to the principal axis.

Steps to Draw a Ray Diagram for a Lens:

1. Draw the lens and mark the optical center (O), principal axis, and focal points (F) on both sides of the lens.
   
2. Place the object at a specific distance from the lens.
   
3. Draw at least two of the three key rays from the top of the object:
   A ray parallel to the principal axis, which refracts through the focal point.
   A ray through the optical center, which continues straight.
   A ray through the focal point, which refracts parallel to the principal axis.
   
4. The point where the rays intersect (or appear to intersect) is the location of the image.
   
5. Determine the image properties (real/virtual, upright/inverted, magnified/reduced).
   

Image Characteristics

• Real Image: Formed when light rays actually converge. Can be projected on a screen.
• Virtual Image: Formed when light rays appear to diverge from a point. Cannot be projected on a screen.
• Upright or Inverted: Depends on the orientation of the image relative to the object.
• Magnified or Reduced: Depends on the size of the image relative to the object.

Converging Lens:
Object beyond 2F: Real, inverted, reduced.
Object between F and 2F: Real, inverted, magnified.
Object inside F: Virtual, upright, magnified.
Diverging Lens:
Always produces a virtual, upright, reduced image.

Ray Diagrams: Converging Lenses
A converging lens (also known as a convex lens) brings light to a focus, resulting in the formation of a real image (an image formed by the convergence of rays of light).
This video explain the principles behind drawing lens ray diagrams for converging lenses and then demonstrate the drawing of two such diagrams:
The first where the object is further from the lens than the focus.
The second where the object is closer to the lens than the focus.

• Show Video

Ray Diagrams of Convex Lens
Describe what is meant by a convex lens?
How to draw ray diagrams to show the formation of an image by a convex lens?

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Ray Diagrams: Diverging Lenses
A diverging lens (also known as a concave lens) is one that causes light passing through it to diverge away from a focus. This can result in the formation of a virtual image. This video explains the rules that can used to draw lens ray diagrams for diverging lenses and demonstrate the construction of one such diagram.

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Try the free Mathway calculator and problem solver below to practice various math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.

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