The process of change from solid directly to vapour is called MCQ with Answer and Explanation

Explanation:
Formula: n = sin[(A+δ_m)/2]/sin(A/2). δ_m depends on prism angle A and refractive index n. Memory tip: 'δ_m increases with A and n; used to measure n'. Optics formula frequently tested in competitive exams.

Explanation:
According to Archimedes' principle, the floating ice displaces a volume of water equal to its own weight. When the ice melts, it transforms into a volume of water that is exactly equal to the volume of water it displaced while floating. Therefore, the water level remains unchanged.

Explanation:
Time period T = 1/f = 1/200 = 0.005 s = 5 ms. Frequency is number of cycles per second. Relationship T = 1/f is fundamental. For 200 Hz, period is 5 milliseconds.