Images by Spherical Lenses MCQs Quiz | Class 10
This quiz on Images by Spherical Lenses for Class X Science (Code 086) from Unit III: Natural Phenomena will test your understanding of image nature, position, and ray diagrams formed by spherical lenses. Attempt all 10 multiple-choice questions, submit your answers to see your score, and download a detailed answer PDF for revision.
Understanding Images Formed by Spherical Lenses
Spherical lenses, which include convex (converging) and concave (diverging) lenses, are fundamental optical components. They form images by refracting light rays, and the characteristics of these images depend crucially on the type of lens and the object’s position.
Key Concepts and Image Formation
Convex Lens (Converging Lens): A convex lens is thicker at the center and thinner at the edges. It converges parallel light rays to a point. It can form both real, inverted images and virtual, erect, magnified images. Real images are formed when light rays actually meet after refraction, while virtual images are formed when rays appear to diverge from a point.
- Object at infinity: Image formed at F2, real, inverted, highly diminished.
- Object beyond 2F1: Image formed between F2 and 2F2, real, inverted, diminished.
- Object at 2F1: Image formed at 2F2, real, inverted, same size.
- Object between F1 and 2F1: Image formed beyond 2F2, real, inverted, magnified.
- Object at F1: Image formed at infinity, real, inverted, highly magnified.
- Object between F1 and Optical Center (O): Image formed on the same side as the object, virtual, erect, magnified. This is used in magnifying glasses.
Concave Lens (Diverging Lens): A concave lens is thinner at the center and thicker at the edges. It diverges parallel light rays. A concave lens always forms virtual, erect, and diminished images, regardless of the object’s position.
- Object at infinity: Image formed at F1, virtual, erect, highly diminished.
- Object between infinity and Optical Center (O): Image formed between F1 and O, virtual, erect, diminished.
Important Ray Tracing Rules for Lenses
- A ray of light parallel to the principal axis, after refraction through a convex lens, passes through its principal focus (F2) on the other side. For a concave lens, it appears to diverge from the principal focus (F1) on the same side.
- A ray of light passing through the principal focus (F1) of a convex lens, or directed towards the principal focus (F2) of a concave lens, emerges parallel to the principal axis after refraction.
- A ray of light passing through the optical center (O) of a spherical lens goes undeviated after refraction.
Quick Revision Points
- A convex lens is a converging lens; a concave lens is a diverging lens.
- Real images are always inverted; virtual images are always erect.
- A concave lens always forms virtual, erect, and diminished images.
- The optical center is a point on the principal axis through which a ray of light passes undeviated.
- Magnification (m) is positive for erect (virtual) images and negative for inverted (real) images.
- Lens formula: 1/v – 1/u = 1/f (where v = image distance, u = object distance, f = focal length).
Practice Questions
Test your understanding further with these additional questions:
- An object is placed at a distance of 2F from a convex lens. Describe the characteristics of the image formed.
- What type of lens is used to correct myopia (short-sightedness)? Explain why.
- A student wants to project the image of a candle flame on a screen using a spherical lens. What type of lens should be used, and what would be the nature of the image?
- If a lens produces a magnification of +2, what does this tell you about the image (nature, size, orientation)?
- State two differences between a real image and a virtual image.
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