The phenomenon of apparent change in frequency due to relative motion between source and observer is called MCQ with Answer and Explanation

Explanation:
Resonance in series LCR circuit occurs when X_L = X_C, i.e., ωL = 1/(ωC) ⇒ ω = 1/√(LC). At this frequency, impedance is minimum (Z=R), current maximum, and circuit is purely resistive. Memory tip: 'Resonance: X_L = X_C; ω₀ = 1/√(LC); series: Z_min, parallel: Z_max'. This AC circuit concept is frequently tested in competitive exams. Always distinguish series and parallel resonance conditions; competitive exams often test series LCR resonance fundamentals.

Explanation:
λ = h/(mv) = 6.63×10⁻³⁴/(1×10) = 6.63×10⁻³⁵ m. Extremely small, not observable. For electron it's significant. de Broglie hypothesis: matter waves. This is modern physics.

Explanation:
Lens maker's formula: 1/f = (μ_lens/μ_medium - 1)(...). In water, relative refractive index reduces, so power decreases, focal length increases. Glass in water behaves less converging.