Final answer:
Therefore, the correct answer is (a) Copper/Iron: 1/√2.To determine the ratios of the diameters of the three wires, we need to consider the tension in each wire.
Step-by-step explanation:
To determine the ratios of the diameters of the three wires, we need to consider the tension in each wire. Since the bar is supported symmetrically, the tension in each wire will be the same.
The tension in a wire can be given as:
T = mg
Where T is the tension, m is the mass of the bar, and g is the acceleration due to gravity.
Since the tension is the same for all three wires, we can equate the tensions and solve for the ratios of their diameters.
Let's denote the diameter of the copper wire as dC and the diameter of the iron wire as dI. We can write the ratio as:
dC/dI = √(ρC/ρI)
Where ρC and ρI are the resistivities of copper and iron respectively. Since the wires have the same resistance, the ratio of their resistivities will be equal to the ratio of their cross-sectional areas.
The correct ratio of the diameters of copper to iron is 1/√2.