A lens has power +1 D. Its focal length in cm is MCQ with Answer and Explanation

Explanation:
Generator uses electromagnetic induction to produce electricity from mechanical motion.

Explanation:
At highest point velocity zero, so K.E. = 0. All converted to P.E.

Explanation:
From floatation: ρ_wood/ρ_water = fraction submerged in water = 0.6. Thus ρ_wood = 0.6 g/cm³ (since ρ_water = 1 g/cm³). In new liquid (ρ_l = 0.8 g/cm³), fraction submerged f = ρ_wood/ρ_l = 0.6/0.8 = 0.75 = 75%. This uses the principle that fraction submerged equals density ratio. Memory aid: 'f = ρ_object / ρ_fluid'. Such comparative buoyancy problems test application of Archimedes' principle across scenarios, common in competitive exams. Always maintain consistent units (g/cm³ here simplifies calculation).