How Things Work
Electricity, Magnetism, Light and Sound
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Overview
"How Things Work" is a core physics theme in the PSTET Paper II Science section, covering four foundational topics that explain everyday phenomena: electricity, magnetism, light and sound. These concepts form the backbone of upper-primary science (Classes VI-VIII) and are tested both for content knowledge and pedagogical understanding.
For PSTET, expect questions on basic definitions, simple circuits, magnetic properties, reflection/refraction of light, and characteristics of sound. The examiner often frames questions around practical applications—why a fuse blows, how an electromagnet works, why we see rainbows, or how sound travels through different media. Mastering these topics requires understanding the underlying principles rather than rote memorisation.
This section bridges the gap between abstract physics and the child's daily experience. A strong grasp here also supports pedagogy questions on activity-based learning and the use of simple experiments in classrooms.
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Key Concepts
**Electricity**
- **Electric current** is the flow of electric charge (electrons) through a conductor; measured in amperes (A).
- A **complete circuit** requires a source (cell/battery), conducting wire, load (bulb/appliance) and a switch; any break stops current flow.
- **Conductors** allow current to pass (metals like copper, iron); **insulators** resist current (rubber, plastic, wood).
- **Heating effect of current**: when current flows through a resistance, heat is produced (used in heaters, fuses, electric iron).
**Magnetism**
- A **magnet** has two poles—north and south; like poles repel, unlike poles attract.
- **Magnetic field**: the region around a magnet where its influence can be felt; represented by field lines running from north to south pole externally.
- **Electromagnet**: a coil of wire wound around an iron core becomes a magnet when current flows; strength increases with more turns or higher current.