The angle of incidence is equal to angle of reflection is the law of MCQ with Answer and Explanation

Explanation:
Kepler's 3rd law: T² ∝ R³ => T' = T (4)^(3/2) = T×8 = 8T.

Explanation:
Beats occur due to interference of two waves with slightly different frequencies (Δf small, typically < 10 Hz for audible beats). The beat frequency is |f₁ - f₂|, causing periodic loudness variation. Same frequency (A, B) produces steady interference (no beats); very different frequencies (D) produce rapid fluctuations not perceived as beats. Memory aid: 'Beats: |f₁ - f₂| small ⇒ audible pulsations; used in tuning'. This wave phenomenon question tests superposition understanding, frequently examined in competitive exams. Always link beat perception to frequency difference magnitude; competitive exams often test qualitative conditions for observable beats.

Explanation:
v = fλ ⇒ λ = v/f = 300/150 = 2 m. Universal wave equation application. Memory tip: 'λ = v/f; units: m/s ÷ Hz = m'. Basic wave property calculation frequently tested in competitive exams to verify formula application.