I think this problem is mostly going to be plug and chug of equations to solve f
ID: 2091079 • Letter: I
Question
I think this problem is mostly going to be plug and chug of equations to solve for power dissipated, and I think I'll be using the equation P = (I^2) * R but I'm not quite sure how the pieces fit together. Can anyone give me a hand getting started please? Thanks.
"Consider three identical light bulbs hooked up to a battery as shown. Find the power dissipated by each bulbs and the total power dissipated by the circuit. In this problem, assume that the battery is a perfect physics battery supplying voltage V and the bulbs are perfect ohmic devices with resistance R.
Then, Bulb C burns out, leaving an open circuit at that location. Find the resulting power dissipated by each of the remaining bulbs and the total power dissipated by the circuit.
The brightness of each bulb is proportional to the power. In your answer, explain if and/or how the relative brightness of each bulb and the total combined brightness of all the bulbs changes when Bulb C burns out. Explain conceptually why your answers make sense."
Explanation / Answer
Nothing happens to the brightness of the light bulbs in the parallel circuit if the power supply is capable of supplying the additional current. Otherwise, the original bulbs will dim according to the additional current demand. Additional information The brightness of each bulb in a circuit is proportional to the power it dissipates, which is equal to: (voltage across this bulb)2 divided by (impedance of this bulb). Neither the voltage across the bulb or the impedance of the bulb depends on how many other bulbs may exist in parallel with this one (unless the power supply is overloaded and the voltage is beginning to 'sag'). Here's a note that may surprise you: All of the light bulbs in your house are in parallel across the utility supply to the house ... as well as everything else that's plugged into a wall outlet. Switching one of them on or off has no effect on the brightness of the others, does it? No, it does not. The observer will note no changes in the brightness of a given bulb when other bulbs are switched on and off. They are all connected in parallel across the same voltage source, which some call the mains.