Young equation γ_lv cos θ = γ_sv − γ_sl (three-phase contact)

Young equation (Young 1805): horizontal force balance at the liquid-solid-vapour contact line determines the contact angle θ. Complete wetting (θ=0) when γ_sv ≥ γ_sl + γ_lv (cos θ = 1, 'spreads'); complete non-wetting (θ=π) in the…