29) This question asks us to find how the brightness of the bulbs changes when we move the bulbs from a series circuit to a parallel circuit. First of all, since bulb X is brighter than bulb Y when in series, we know that one bulb must have greater resistance than the other. For problems like this, it is easiest to explain using example numbers.
As a reminder, a bulb can be treated like a resistor, and the brightness of a bulb is determined by the power it dissipates.
Let's just use example numbers and solve for the power dissipated. by each resistor.
Remember that the question told us that when in series, bulb X is brighter. This means we can rename the 4 Ohm resistor, R[1], as bulb X, and R[2] as bulb Y.
Next, we can take a look at the bulbs in parallel.
Answer: E
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