The unit of electric power can be expressed as MCQ with Answer and Explanation

Explanation:
g=0 at centre, so weight zero.

Explanation:
Total internal reflection (TIR) is exploited in optical fibers for light transmission with minimal loss (core-cladding interface). In diamonds, high refractive index (n≈2.4) gives small critical angle (~24°), so most light undergoes TIR, enhancing brilliance through multiple reflections. Memory aid: 'TIR applications: optical fibers (communication), diamonds (sparkle), prisms (binoculars)'. This application question tests optics uses, frequently appearing in competitive exams. Always link physical principles to technological applications; competitive exams emphasize practical relevance of theoretical concepts.

Explanation:
COP = desired output/work input = 300/100 = 3. Typical COP > 1 for refrigerators. Memory aid: 'COP = cooling effect per work; higher = more efficient'. Thermodynamics calculation frequently tested in competitive exams.