In which of the circuits shown does a current exist to light the bulb?
Solution 9E In the first figure the bulb is not connected to the circuit. One of terminal of the bulb is just connected to the point where the tow wires are connected. So the current will not flow through the bulb, the current will flow through the wires only. In the second case, only the bottom wire is completing the circuit. The upper wire, which is connected to the bulb is not completing the circuit and hence there will not be any through this wire and hence through bulb. In the third figure, both of the wire connected to the same terminal of the battery and same terminal of the bulb. Hence the circuit is incomplete and hence there will be no current flow. In the fourth figure, the bottom wire is connected to the glass part of the bulb, which is an insulator. Hence, again the circuit is incomplete and there will be no current through. In the fifth figure, the bottom wire connected to the one terminal of the bulb. Then, from the other terminal the top wire is connected to the other terminal of the battery and hence completing the circuit. Hence there will be current in this circuit. So in the fifth circuit, the current exist in the light bulb.