Voltage across Parallel Resistances

Imagine a set of ornamental light bulbs connected in parallel following figure. This is the method used for outdoor holiday lighting or for bright indoor lighting. It’s easier to repair a parallel-wired string of such lights if one bulb should burn out than it is to fix a series-wired string. And in the parallel configuration, the failure of one bulb does not cause total system failure.

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In a parallel circuit, the voltage across each component is equal to the supply or battery voltage. The current drawn by each component depends only on the resistance of that particular device. In this sense, the components in a parallel-wired circuit operate independently, as opposed to the series- wired circuit in which they all interact.

If any one branch of a parallel circuit opens up, is disconnected, or is removed, the conditions in the other branches do not change. If new branches are added, assuming the power supply can handle the load, conditions in previously existing branches are not affected.