The phenomenon of superconductivity is characterized by: MCQ with Answer and Explanation

Explanation:
Magnetic field lines form concentric circles around a straight current-carrying wire, with direction given by right-hand thumb rule (thumb in current direction, fingers curl in field direction). This is derived from Biot-Savart law or Ampère's circuital law. Memory tip: 'Right-hand rule: thumb = current, fingers = field circles'. This fundamental field pattern is frequently tested in competitive exams. Always visualize field direction: for current toward you, field lines are counterclockwise. Distinguish from solenoid field (axial inside) or bar magnet (dipole pattern).

Explanation:
The principle of homogeneity states that you can only add or subtract physical quantities that have the exact same dimensional formula (you can't add mass to length). Therefore, in the equation A = B + C, the terms B and C must have the same dimensions, and their sum will yield a quantity A that also shares those exact same dimensions.

Explanation:
The effective acceleration due to gravity at latitude lambda is g' = g - R * w^2 * cos^2(lambda), where w is angular velocity. At the equator, lambda = 0, so cos(0) = 1. This subtracts the maximum outward centrifugal acceleration (Rw^2) from g. At the poles, lambda = 90, centrifugal effect is zero. Thus, g is minimum exactly at the equator.