General Science: Everyday Applications of Class 6-10 Concepts
General Science here is Class 6-10 physics, chemistry, biology and environment, tilted towards everyday applications: why a particular mirror is used, which deficiency causes which disease, what an alloy contains, what a food chain represents. Definitions alone are not enough because the question usually asks for a reason.
High-yield areas
- Physics: units and symbols, types of motion, reflection and refraction, lenses and mirrors, sound (fastest in solids), electric current, Ohm's law, magnetic effects of current.
- Chemistry: element symbols, acids, bases and indicators, common salts, alloys (brass = copper + zinc, bronze = copper + tin, steel = iron + carbon), combustion and fuels.
- Biology: cell organelles, digestive, respiratory, circulatory and excretory systems, vitamins and deficiency diseases, blood groups, photosynthesis.
- Environment: food chains and trophic levels, biodegradable waste, greenhouse gases, the ozone layer.
Worked example
Why is a concave mirror used as a shaving mirror? Reasoning: when the face lies within the focal length of a concave mirror, the image is virtual, erect and magnified. A convex mirror always gives a diminished erect image and a plane mirror gives an erect image of the same size. Answer: concave mirror, because of the magnified erect image.
Traps that cost marks
- Mass versus weight: weight changes with gravity, mass does not.
- Sound travels faster in solids than in air, while light travels faster in air than in glass.
- Vitamin pairings: A with night blindness, B1 with beriberi, C with scurvy, D with rickets, K with clotting.
- Physical versus chemical change, and reversible versus irreversible change.
- Food-chain arrows show the direction of energy flow, not simply who eats whom.