Is current always equally split in a parallel circuit with two branches? one branch has 2 bulbs, the other 3 bulbs. 2 3V cells are connected. The branch with 2 bulbs has 3A, but then how much will the other one have?
1 Answer
No, it is not always equally split (it often is when you first meet parallel branches for simplicity.)
Explanation:
We need to assume that all the bulbs are equivalent (in terms of resistance) and can then determine the current flowing through each branch.
The current splits in inverse proportion to the resistance (a bigger current will pass through the branch with less resistance) so if two bulbs has a current of 3A, then a branch with 3 bulbs will have a current of 2A flowing through it.
We can prove this by finding the resistance of the bulbs by Ohm’s law (remember: the branches in a parallel circuit always have the same p.d. or voltage across them - the full p.d./voltage of the cells.)
In the first branch we know p.d. = 2 x 3 = 6V, so as resistance is defined as the voltage per unit current
As each bulb is the same and in the 2nd branch we have three bulbs in series, the total resistance of this branch will be 3
Thus the current flowing (by Ohm’s law) is given by
