The process of coating iron with zinc to prevent rusting is called
A. Annealing
B. Alloying
C. Galvanisation
D. Electroplating
Answer: Option C
Solution (By JKSSB Mock Tests)
Galvanisation: iron/steel coated with zinc to prevent corrosion. Zinc acts as sacrificial anode. Electroplating deposits metal layer using electricity. Alloying mixing metals. Annealing heat treatment.
Explanation:
sin C = 1/μ = 2/3 ≈ 0.6667, C = sin⁻¹(2/3). So option A: sin⁻¹(2/3). Wait sin C = n2/n1 = 1/1.5 = 2/3. So C = sin⁻¹(2/3). Option A is sin⁻¹(2/3). I'll correct to A.
Explanation:
Dimensionless quantities: angle (radian = arc/radius), strain (ΔL/L), refractive index (ratio of speeds). All have [M⁰L⁰T⁰]. Memory aid: 'Ratios of same dimensions ⇒ dimensionless'. Dimensional analysis question frequently tested in competitive exams to identify dimensionless physical quantities.
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