Question
Please help.
In circuit III (redrawn below), the terminals of bulbs D and E are connected together and each junction is then connected by another wire to the battery. Also In the figure below (circuit IV) is an arrangement, which has each bulb D and E with its own connection to the battery. Will the bulb brightness in circuit IV be the same or different than what you observed earlier for the same bulbs in circuit III? Explain your thinking. Are there any differences between circuit III and IV? Use circuit III or IV to describe the current flow around the entire parallel circuit. What do your observations about bulb brightness suggest about the way the current through the battery divides and recombines at the junctions where the circuit splits into the two parallel branches? What do your observations about bulb brightness suggest about the relative amounts of current through the battery in a single-bulb circuit (circuit I) and in a circuit in which two identical bulbs are connected in parallel across the battery (circuit III or IV)? That is, how does the battery current in circuit l compare to battery current in circuit III?
Explanation / Answer
a) The brightness of the bulbs in both the circuits will be same because even though the arrangement is a little different, both of the bulbs are conneceted in parallel to the battery. So the brightness will be same.
b) When the circuit is divided in to two parallel branches, the current gets divided between the two branches depending upon the resistance of the bulbs. if the resistance is same for both the bulbs then the current will be divided equally.
c) In a single bulb circuit, the brightness will be more than the individual bulbs in the parallel circuit. And the current in the single bulb circuit is the sum of the currents in each bulb of the parallel circuit.