Genius Maker - School software - Physics software MIRRORS AND LENSES - LENS FOCAL LENGTH

Features:

The Lens and Mirrors ( Lens Focal Length ) is a physics software, which facilitates to solve optical physics problems related to mirrors and lenses. The supported mirrors and lenses are as follows

• Plain glass

• Convex lens

• Concave lens

• Plain mirror

• Convex mirror

• Concave mirror

How to start with Mirrors and Lenses ( Lens Focal Length ) software ?

• Open Genius Maker software and click "Lenses and Mirrors" button. It opens the Lenses and Mirrors window as shown above.
• On opening you will see that the convex lens is selected by default. An arrow (which is the object) is placed at a distance of 50 units from lens and its image is formed on the other side at a distance of 75 units form lens.
• You may try moving the object by clicking it by mouse and then dragging. You may see that the object moves horizontally along with mouse pointer and the image location changes according to the focal length of the lens. The parameters, such as object distance, image distance, magnification factor and the nature of image also changes according to the position.
• Now let us try changing the "Diagram type". Let us click "Parallel rays from object" from "Diagram type" window on top.
• You may notice that the graphics changes accordingly.
• Let us solve a few sample optical physics problems by using this software.

EXAMPLE - 1

• An object is kept at a distance of 75 cm from a convex lens of focal length 20 cm. Find the distance between its image and lens. Also explain the nature of the image.

• Ensure that "Convex lens" is selected from the "Type of lens / mirror" box. If not, select it.

• Enter the values for object distance and focal length as 75 and 20 respectively.

• The graphics area, now automatically displays the problem situation. It displays the distance of image as 27.2727 (If image or object is not visible, just click "Zoom all")

• Hence the answer to the current problem is 27.2727 cm.

• The detailed nature of image can be found on the top-right location of the graphics area.

• The magnification factor displayed is -0.3636 ( Negative sign indicates that the image is inverted)

• With this, we can explain the nature of image as follows.

  • The image of the current problem is a real image, which is inverted and diminished compared to the object. The magnification factor is -0.3636

• Now you may move the object by clicking and dragging it by mouse and see how the image changes. 

• Also you may use and practice the zoom control buttons. The description of zoom control buttons are as below. (Please note that the zoom functions of "Lens and Mirrors" software module is meant for only horizontal zooming and not vertical zooming.)  

  • "Zoom in" :  To zoom into the graphics area

  • "Zoom out" :  To zoom out of the graphics area

  • "Zoom all" :  To zoom the graphics area, in such a way to include both object and image. (When the distance of image formed is a very very high value, it cannot be displayed.) 

  • "Standard Zoom" :  To show the graphics area with 3 times the distance of focal length on both sides of the lens.

EXAMPLE - 2

• An object is kept at a distance of 620 cm from a convex lens of focal length 12 cm. Find the distance between its image and lens. Also explain the nature of the image.

• Ensure that "Convex lens" is selected from the "Type of lens / mirror" box. If not, select it.

• Enter the values for object distance and focal length as 620 and 12 respectively.

• The graphics area, now automatically displays the problem situation. But the object is not visible in the graphics area. This is because the object is beyond the visible. Just click "Zoom all" button. Now the graphics area gets zoomed out to include the object. You may notice that the size of the image is too small. The software displays the distance of image as 12.2368

• Hence the answer to the current problem is 12.2368 cm.

• The detailed nature of image can be found on the top-right location of the graphics area.

• The magnification factor displayed is -0.0197 ( Negative sign indicates that the image is inverted)

• With this, we can explain the nature of image as follows.

  • The image of the current problem is a real image, which is inverted and diminished compared to the object. The magnification factor is -0.0197

• Now you may move the object by clicking and dragging it by mouse and see how the image changes. 

EXAMPLE - 3

• An object is kept at a distance of 140 mm from a concave mirror of focal length 300 mm. Find the distance between its image and lens. Also explain the nature of the image.

• Select "Concave mirror" from the "Type of lens / mirror" box.

• Enter the values for object distance and focal length as 140 and 300 respectively.

• The graphics area, now automatically displays the problem situation. It displays the distance of image as -262.5 (If image or object is not visible, just click "Zoom all")

• Hence the answer to the current problem is -262.5 cm. (negative sign is because the object is behind the mirror)

• The detailed nature of image can be found on the top-right location of the graphics area.

• The magnification factor displayed is 1.875 ( Positive sign indicates that the image is upright)

• With this, we can explain the nature of image as follows.

  • The image of the current problem is a virtual image, which is upright and magnified compared to the object. The magnification factor is 1.875

• Now you may move the object by clicking and dragging it by mouse and see how the image changes.

• You may try moving the object after selecting the other types of lenses and mirrors, namely, plain glass, concave lens, plain mirror, concave mirror etc to see how the image is formed in those lenses and mirrors.

Additional Features

• Diagram types: This software supports display of rays in 2 different ways, namely, Ray diagram and Parallel rays from object. The ray diagram shows path of three rays from object to image, which are the regular convention in optical physics. The second option, "parallel rays from object", shows the path of 9 parallel rays emanating from object towards image.

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