The specific resistance (resistivity) of a metallic conductor depends exclusively upon its:
A. Nature of material and temperature
B. Length
C. Volume
D. Cross-sectional area
Answer: Option A
Solution (By JKExamLibrary)
Resistance depends on length and area (R = rho * L / A), but specific resistance or resistivity (rho) is an intrinsic property of the material itself. It does not depend on the geometric dimensions of the conductor (length, area, volume). Resistivity strictly depends on the atomic structure (nature of the material) and the thermal vibrations (temperature of the material).
Explanation:
The acceleration due to gravity at a depth 'd' is given by g' = g(1 - d/R), where R is the radius of the Earth. If we go to the center of the Earth, the depth 'd' becomes exactly equal to R. Substituting d = R into the formula gives g' = g(1 - R/R) = g(1 - 1) = 0. So, gravity is zero at the core.
Explanation:
Parallel branches share same voltage (potential difference). Current divides inversely with resistance. Memory aid: 'Parallel: same voltage; Series: same current'. Fundamental circuit property frequently tested in competitive exams to assess basic electronics understanding.
Explanation:
Isaac Newton formulated the universal law of gravitation in his Principia Mathematica (1687), stating F = Gm₁m₂/r². Galileo studied falling bodies; Kepler derived planetary motion laws; Einstein developed general relativity (gravity as spacetime curvature). Memory aid: 'Newton = gravity apple story'. This history-based question tests knowledge of key scientific contributions, frequently appearing in competitive exams. Always associate scientists with their specific discoveries to avoid confusion between classical and modern physics pioneers.
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