A convex lens is immersed in a liquid of same refractive index. Its focal length becomes MCQ with Answer and Explanation

Explanation:
(1/2)^n = 1/16 => n=4 half-lives in 20 days => half-life = 5 days.

Explanation:
Materials are classified by their magnetic properties. Ferromagnetic materials (Iron, Cobalt, Nickel) are strongly attracted to magnets. Paramagnetic materials (Aluminum, Platinum) are weakly attracted. Diamagnetic materials (Water, Bismuth, Copper, Gold) are actually weakly repelled by a magnetic field because they create an induced magnetic field in opposition to the externally applied one.

Explanation:
1 g/cm³ = 1000 kg/m³, so 8 g/cm³ = 8000 kg/m³.