two solenoids are made with the same cross sectional area and total number of turns. inductor b is twice as long as inductor a;

d. 2.14 x 10⁻⁴ kg/m³

Explanation:

Density is defined as the mass of an object per unit volume occupied by that object. The formula of density is, therefore, given as follows:

where,

ρ = density of platinum band = ?

m = mass of platinum band = 3 x 10³ kg

V = Volume displaced by Platinum band = 1.4 x 10⁷ m³

Therefore,

Hence, the correct option is:

d. 2.14 x 10⁻⁴ kg/m³