Answer:
a. R2b = R/4
Explanation:
The total resistance of a metallic wire is given by the following formula:
R = ρL/A
where,
R = Resistance of Wire
ρ = Resistivity of the material of wire
L = Length of Wire
A = Area of Wire = πr²
Therefore,
R = ρL/πr²
for the 1st wire,
radius = r = b
Therefore,
R = ρL/πb² ----------- equation 1
Now, for the second wire,
r = 2b
Therefore,
R2b = ρL/π(2b)²
R2b = ρL/πb²4
using equation 1:
R2b = R/4
therefore, correct option is:
a. R2b = R/4
