LED stands for MCQ with Answer and Explanation

Explanation:
A Venturimeter consists of a converging pipe, a narrow throat, and a diverging pipe. As fluid passes through the constricted throat, its velocity increases. According to Bernoulli's principle, this increase in kinetic energy must be accompanied by a strictly corresponding decrease in fluid pressure. By measuring this pressure difference, the flow rate can be precisely calculated.

Explanation:
Acceleration due to gravity at height h: g' = gR²/(R+h)², where R is Earth's radius. Given h = R, so g' = gR²/(2R)² = gR²/4R² = g/4. This inverse square law dependence arises from Newton's law of gravitation. At depth, variation differs, but for height, this formula applies. Memory aid: Double the distance from center ⇒ gravity becomes one-fourth. This standard result is frequently tested in gravitation sections of competitive exams. Always verify whether height or depth is specified, as formulas differ significantly.

Explanation:
For myopia, corrective lens forms image of distant object at far point. 1/f = 1/(-far point) - 1/(-∞) => -2 = -1/F => F = 0.5 m = 50 cm.