The instrument used to record seismic waves is MCQ with Answer and Explanation

Explanation:
Newton's law of gravitation: F = G·m₁m₂/r². Thus force is directly proportional to the product of the masses (m₁m₂) and inversely proportional to square of distance (r²). Option D incorrectly states 'directly proportional to square of distance' – it's inverse square. This fundamental law governs celestial mechanics. Memory tip: 'F ∝ m₁m₂ and F ∝ 1/r²'. Competitive exams often test precise wording of physical laws; distractors may reverse proportionality or misstate dependencies. Always recall the exact mathematical form.

Explanation:
Seconds pendulum has period 2 s (1 s each swing).

Explanation:
Werner Heisenberg, a German theoretical physicist, published his famous Uncertainty Principle in 1927. The principle dictates a fundamental limit to precision at the quantum level: the more precisely the position of a particle (like an electron) is determined, the less precisely its momentum can be known, and vice versa. Mathematically, delta_x * delta_p >= h/(4pi).