Atmospheric pressure at sea level is about MCQ with Answer and Explanation

Explanation:
For myopia, corrective lens forms image of distant object at far point. 1/f = 1/(-far point) - 1/(-∞) => -2 = -1/F => F = 0.5 m = 50 cm.

Explanation:
Wavelength is distance between successive compressions or rarefactions.

Explanation:
For low Earth orbit (r ≈ R_earth), orbital period T = 2π√(r³/GM). Using g = GM/R², T = 2π√(R/g). With R = 6.4×10⁶ m, g = 9.8 m/s², T ≈ 2×3.14×√(6.4e6/9.8) ≈ 6.28×√(653061) ≈ 6.28×808 ≈ 5076 s ≈ 84.6 minutes. Memory aid: 'Low orbit period ≈ 84 min; geostationary = 24 hours'. This standard result is frequently tested in competitive exams. Always recall that period increases with orbital radius; competitive exams often compare low orbit vs geostationary periods.