Everyday Science
Everyday science asks why familiar things behave as they do. Every answer is one physics or chemistry principle wearing ordinary clothes, so the skill is translating the household object back into the principle.
Mental model
Everyday science is textbook physics and chemistry wearing kitchen clothes. For each household item ask 'which single principle is being exploited?' — pressure cooker/boiling point rises with pressure, thermos/three modes of heat transfer blocked, microwave/water molecules absorbing radiation, refrigerator/evaporation absorbs heat, fuse/heating effect of current. Store item and principle as a pair; the exam gives you one and asks for the other.
Associations
A short trigger on the left, everything it pulls with it on the right.
Pressure changes boiling point.
A pressure cooker raises the pressure so water boils above 100 degrees and food cooks faster; on a mountain the pressure is lower, water boils cooler, and cooking takes longer. One principle, two everyday facts.
Scattering explains both the blue sky and the red sunset.
Shorter wavelengths scatter more, so the daytime sky is blue. At sunset light travels a longer path through the atmosphere, the blue is scattered away, and what reaches the eye is red. Same cause, opposite-looking results.
Things to remember
The night-before list. Short enough to recall cold.
- 1A pressure cooker cooks faster because higher pressure raises water's boiling point.
- 2An electric fuse is a deliberately weak link that melts and breaks the circuit when current exceeds a safe value.
- 3A refrigerator cools by evaporating a refrigerant inside and condensing it outside, moving heat from inside to the room.
- 4LPG cylinders carry an odorant added on purpose, because the gas itself is odourless and leaks would otherwise go undetected.
- 5Hard water lathers poorly with soap because dissolved calcium and magnesium salts form an insoluble scum.
- 6Iron rusts only in the presence of both air and moisture, which is why oiling, painting or galvanising prevents it.
In detail
- A pressure cooker cooks faster because higher pressure raises the boiling point of water above 100 degrees Celsius.
- An electric fuse works on the heating effect of current and is always connected in the live wire, in series with the appliance.
- Soap cleans because one end of its molecule is water-loving and the other is oil-loving, so it lifts grease into water as micelles.
- Sweating cools the body because evaporation absorbs latent heat from the skin.
- The sky looks blue because shorter blue wavelengths scatter more than red in the atmosphere; at sunrise and sunset the light travels a longer path, so red dominates.
Where people slip
- A refrigerator does not create cold; it moves heat out. Options describing it as producing cold are conceptually wrong.
Check yourself
Nothing here is scored — it will not change your mastery figures.
Cooking takes longer at high altitudes because:
From the question bank
LPG (Liquefied Petroleum Gas), commonly used for cooking, is mainly a mixture of which two gases?
From the question bank
Rust, formed when iron is exposed to moist air, is chemically known as what?
Books to read
- NCERT Class IX — Science
- NCERT Class X — Science
- Lucent's General Knowledge
Official sources
Hand-checked official domains only — the notes above carry no links of their own.