Question

Both batteries in (Figure 1) are ideal and identical, and all lightbulbs are the same.

Rank in order, from brightest to least bright, the brightness of bulbs a to c.

Answer 1

In the first case, only bulb \(a\) is connected to the battery and thus total voltage of the battery will passes through bulb \(a\).

In second case, two bulbs \(b\) and \(c\) are connected to the battery in parallel. Since bulbs \(b\) and \(c\) are connected to the battery in parallel, the voltage through bulbs \(b\) and \(c\) must be equal.

Thus, the voltage through all three bulbs is same.

Thus, the order of brightness of the bulbs is \(a=b=c\).