If an air bubble of diameter \( 2 \, \text{mm} \) rises steadily through a liquid of density \( 2000 \, \text{kg}/\text{m}^{3} \) at a rate of \( 0.5 \, \text{cm}/\text{s} \), then the coefficient of viscosity of liquid is ________ Poise. (Take \( g = 10 \, \text{m}/\text{s}^{2} \))
