Gravitational force between two masses varies with distance r as:
A. 1/r²
B. r²
C. 1/r
D. r
Answer: Option A
Solution (By JKSSB Mock Tests)
Newton's law: F = Gm₁m₂/r² ⇒ F ∝ 1/r². Inverse square law fundamental to gravitation, electrostatics, and radiation intensity. Memory aid: 'Gravity weakens with square of distance; double distance ⇒ force becomes 1/4'. Core concept frequently tested to verify understanding of fundamental force laws in competitive exams.
Explanation:
Step-up transformer increases voltage and decreases current proportionally (P = V×I constant ideal). Power constant (ignoring losses). Used in power transmission to reduce I²R losses. Step-down decreases voltage.
Explanation:
Solar cells (photovoltaic cells) convert light energy (photons) directly into electrical energy via the photovoltaic effect: photons excite electrons in semiconductor material, creating electron-hole pairs that generate voltage. This is distinct from solar thermal (light to heat to electricity) or batteries (chemical to electrical). Memory aid: 'Photo = light; voltaic = electricity'. This renewable energy application question tests knowledge of energy conversion principles, common in competitive exams. Always distinguish photovoltaic (direct light-electricity) from other solar technologies.
No comments yet. Be the first to start the discussion!