Physics Practice: Refraction through Lenses (Mock Test 4 - Expert)
1. Expert Analysis: A point source of light is placed at a distance of $20 \text{ cm}$ from a convex lens of focal length $10 \text{ cm}$. On the other side, a concave lens of focal length $5 \text{ cm}$ is placed at a distance $d$ from the convex lens. If the final image is formed at infinity, then $d$ is:
2. Experimental Logic: In the displacement method, the distance between the object and the screen is $D$. A convex lens of focal length $f$ forms two sharp images for two positions of the lens. The condition for this to happen is:
3. Data-Based: A lens has a refractive index of $1.5$. If it is immersed in a liquid of refractive index $1.6$, its nature will change and its focal length will:
4. Clinical Logic: A person uses a lens of power $-2.0 \text{ D}$ for far vision. The focal length and the type of lens are:
5. For a thin lens, the Power ($P$) in terms of refractive index ($\mu$) and radii of curvature ($R_1, R_2$) is given by:
6. An object of height $5 \text{ cm}$ is placed $20 \text{ cm}$ in front of a convex lens. If a real image of height $10 \text{ cm}$ is formed, the focal length is:
7. Expert Application: Why are photographic camera lenses often "coated" with a thin film?
8. A convex lens forms a virtual image when the object distance ($u$) is:
9. The magnifying power of a simple microscope is given by (where $D$ is least distance of distinct vision):
10. If the aperture of a lens is halved, then:
11. A ray of light incident on a convex lens parallel to its principal axis. After refraction, it passes through $F_2$. This ray follows which path?
12. Data-Logic: A lens of power $+5 \text{ D}$ is placed in contact with a lens of power $-1 \text{ D}$. The focal length of the combination is:
13. In the formation of an image by a concave lens, the image is ALWAYS:
14. When two thin lenses of focal lengths $f_1$ and $f_2$ are in contact, the effective focal length $F$ is:
15. A real image is formed by a convex lens. If the magnification is $-2.0$, and the object is at $15 \text{ cm}$, the image is at:
16. The focal length of a plano-convex lens of refractive index $1.5$ and radius of curvature $20 \text{ cm}$ is:
17. Which of the following diagrams correctly shows a ray passing through the optical center?
18. To produce a highly magnified real image using a convex lens, the object should be placed:
19. If an object is placed at the center of curvature of a convex lens surface, the ray incident from it will be:
20. Expert Observation: A convex lens is used to form a real image of a candle flame on a screen. If the lower half of the lens is painted black, then: