As Simple Microscopes: Watch repairers and palmists use convex lenses as simple microscopes to magnify small objects for detailed examination.
For Concentrating Sunlight and Aiding in Reading: Convex lenses can also be used as burning glasses to concentrate sunlight and create a focused beam of light, as well as reading glasses to aid people with presbyopia in reading and other close-up tasks.
VSAQ-2 : Complete the following ray diagram.
VSAQ-3 : Does the focal length of lens of same in all media ? Guess and write.
Variation of Focal Length in Different Media: No, the focal length of a lens is not the same in all media.
Influence of Refractive Index: The focal length of a lens changes when it is placed in different media with varying refractive indices.
Effect of Light Bending: When light passes through different media, it bends at different angles, affecting the path and focal length of the lens.
Conclusion on Focal Length Variability: Therefore, the focal length of a lens is not constant and may vary depending on the medium in which it is placed.
VSAQ-4 : Complete the following ray diagram.
VSAQ-5 : What happens to the image, if a convex lens is made up of two different transparent materials, as shown in figure ?
Effect of Different Materials on Convex Lens: When a convex lens is made up of two different transparent materials with different refractive indices, it will create two images.
Light Bending at Material Interface: This is because light rays passing through the lens will bend differently at the interface between the two materials due to the change in refractive index.
Formation of Two Images: Each interface will produce its own image, resulting in the formation of two images instead of one.
Dependency on Refractive Indices and Curvature: The position and characteristics of these images will depend on the specific refractive indices and curvature of the lens surfaces.
VSAQ-6 : Write the list of materials required for the experiment to find the focal length of a convex lens.
Primary Equipment:
Convex lens (with known focal length)
Optical bench or meter scale
Lens holder or lens stand
Light Source and Projection Screen:
Candle or light source
White screen or a piece of paper
Measurement Tools:
Ruler or measuring tape
Protractor (optional)
Additional Accessories:
Lens cleaning cloth (for maintenance)
Stand or clamp (for supporting the light source)
Purpose of Materials: These materials are essential for setting up and conducting the experiment to determine the focal length of a convex lens through the lens formula or graphical method.