Chapter 23, Problem 85A

To determine

To explain: The effect of failure of one lamp on the current through the other two lamps in a three-lamp parallel circuit.

Answer to Problem 85A

The total current flowing in the circuit gets divided between the remaining two lamps .

Explanation of Solution

Given:

A parallel circuit consisting of three lamps and one lamp burns out.

Consider the parallel circuit of three lamps as shown in Figure 1

  

In a parallel circuit, the same voltage appears across all the lamps. The current is divided between each of the lamps and they sum up to give the total current of the circuit. When one of the lamps, say L₁ burns out, the it creates an open path in that particular branch of the circuit, and hence, the current flow is not possible through the same. However, as evident from the circuit in Figure 1, the current flow through the remaining two lamps remains unaffected. Now, the total current is divided among the remaining two lamps.

Conclusion:

The current flow through the other two lamps in the parallel circuit is maintained even if one lamp burns out.