To determine what happens to the current flow through the branches in a two-branch parallel current divider network when the resistance of one branch is doubled, we can use the current divider rule.
The current divider rule states that the current through a particular branch in a parallel network is inversely proportional to the resistance of that branch compared to the total resistance of the network.
Let's assume that the resistance of the first branch is increased by a factor of 2 while the resistance of the second branch remains the same.
Step 1: Calculate the equivalent resistance of the network
The equivalent resistance of a parallel network can be calculated using the formula:
\frac{1}{R_{eq}} = \frac{1}{R_1} + \frac{1}{R_2}
where R_{eq} is the equivalent resistance, R_1 is the resistance of the first branch, and R_2 is the resistance of the second branch.
Since the resistance of the second branch remains unchanged, we can write:
\frac{1}{R_{eq}} = \frac{1}{(2R_1)} + \frac{1}{R_2}
Simplifying, we get:
\frac{1}{R_{eq}} = \frac{3}{2R_1}
Therefore, the equivalent resistance, R_{eq}, is:
R_{eq} = \frac{2R_1}{3}
Step 2: Calculate the current through each branch
Using the current divider rule, the current through the first branch can be calculated as:
I_1 = \frac{V}{R_1}
where V is the voltage across the parallel network.
Similarly, the current through the second branch is:
I_2 = \frac{V}{R_2}
Step 3: Calculate the new currents after doubling the resistance of the first branch
After doubling the resistance of the first branch, the new resistance becomes 2R_1.
Using the current divider rule, the new current through the first branch, I_1', can be calculated as:
I_1' = \frac{V}{2R_1}
The current through the second branch, I_2', remains the same:
I_2' = \frac{V}{R_2}
Answer: The current through the doubled resistance branch decreases, and the current through the other branch remains unchanged. (Option b)