Which is the most penetrating radiation? MCQ with Answer and Explanation

Explanation:
Dimensionless quantities: angle (radian = arc/radius), strain (ΔL/L), refractive index (ratio of speeds). All have [M⁰L⁰T⁰]. Memory aid: 'Ratios of same dimensions ⇒ dimensionless'. Dimensional analysis question frequently tested in competitive exams to identify dimensionless physical quantities.

Explanation:
Freezing point 0°C = 32°F.

Explanation:
In a parallel-sided glass slab, refraction at first surface bends ray towards normal; at second surface (glass to air), it bends away by equal angle, making emergent ray parallel to incident ray but shifted laterally. No net deviation, only displacement. Memory aid: 'Slab: emergent ray parallel to incident; prism: emergent ray deviated'. This ray optics concept is frequently tested in competitive exams. Always distinguish slab (parallel faces) from prism (non-parallel faces) behavior: slab causes lateral shift, prism causes angular deviation.