A positively charged particle is projected precisely parallel to a uniform magnetic field. The trajectory of the particle will be a: MCQ with Answer and Explanation

Explanation:
According to Gauss's Law in electrostatics, all excess charge on a conducting body resides entirely on its outer surface. Since there is no net charge enclosed within the hollow interior, the electric flux and consequently the electric field everywhere inside the hollow conducting sphere is exactly zero.

Explanation:
Significant figures rules: leading zeros are not significant; trailing zeros after decimal are significant. Thus 0.00250: leading zeros (before 2) not significant; digits 2,5,0 are significant (trailing zero after decimal counts). So three significant figures. Memory tip: 'Start counting at first non-zero digit; include trailing zeros after decimal'. This measurement precision concept is frequently tested in competitive exams. Always apply rules consistently: 0.0025 has two sig figs; 0.00250 has three, indicating higher precision.

Explanation:
Work W = F·d = Fd cosθ. cos0° = 1 gives maximum work. At 90°, cos90° = 0, work zero. For given magnitudes, maximum when force parallel to displacement. This is basic definition.