Why are the bulbs in Figures B, C and D not lighting up?
Answer»
In B, the blue wire is broken. Hence circuit is incomplete and current does not flow. Therefore, bulb will not light up.
In C, the red wire is broken. Hence circuit is incomplete and current does not flow. Therefore, bulb will not light up.
In D, both wires are connected to the same terminal. Hence, there is no potential difference and current does not flow. Therefore, bulb will not light up.