A convex lens is immersed in water. Its focal length
A. Increases
B. Decreases
C. Becomes infinite
D. Remains same
Answer: Option A
Solution (By JKSSB Mock Tests)
Lens maker's formula: 1/f = (μ_lens/μ_medium - 1)(...). In water, relative refractive index reduces, so power decreases, focal length increases. Glass in water behaves less converging.
Explanation:
Ionosphere contains ions and free electrons, reflects radio waves back to Earth, enabling long-distance radio communication. Used in skywave propagation. Troposphere weather layer.
Explanation:
Conservative forces (gravity, spring, electrostatic) have path-independent work; work done over any closed loop is zero. This defines conservative forces and enables potential energy definition. Non-conservative forces (friction) have non-zero closed-path work. Memory aid: 'Conservative force: ∮F·dr = 0; enables energy conservation'. This mechanics concept is frequently tested in competitive exams. Always link conservative forces to potential energy and mechanical energy conservation; this is foundational for advanced physics problem-solving.
Explanation:
By definition, the electric potential difference between two points in an electric field is the amount of external work required to move a unit positive charge (1 Coulomb) slowly and without acceleration from one point to the other against the electrostatic force. The SI unit of potential difference is the Volt (Joules/Coulomb).
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