Two lightbulbs, one rated 60 W at 120 V and also the other rated 100 W at 120 V, are arranged in two various circuits.

You are watching: Which has a larger resistance, a 60 w lightbulb or a 100 w lightbulb?

1. Calculation the resistance of each bulb.


, for this reason


because that the 60 W bulb.

because that the 100 W bulb.

2. Explain what the 60 W and 100 W ratings mean.

Answer: The bulbs room designed come be associated directly to a 120 V source. As soon as you run the bulbs as designed, they will dissipate the rated power. If they dissipate an ext than the rated power, lock are most likely to burn out.

3. Which of the following quantities determines the brightness of a lightbulb?

Answer: c. Power

4. Which of the complying with quantities need to be the same for each bulb in a series circuit?

Answer: a. Current

5. If both lightbulbs are associated in parallel to a 120 V source, which is brighter? define your answer briefly.

Answer: The pear rated at 100 W will be brighter. As soon as both bulbs are connected to the rated voltage, they will dissipate the rated power. The brightness the a bulb counts on the strength it dissipates, for this reason the 100 W bulb will certainly be brighter than the 60 W bulb.

6. If both lightbulbs are linked in parallel come a 50 V source, i beg your pardon is brighter? Explain.

Answer: currently the bulbs will certainly each be dimmer than once they"re associated to 120 V. But the 100 W bulb will certainly still it is in brighter. No matter what a bulb is connected to, that is resistance is a home of the bulb. Parallel bulbs must take the same voltage. By the equation for power , the bulb through the lower resistance will dissipate much more power. The 100 W bulb has a smaller resistance, for this reason it will certainly be the brighter bulb.

7. If both lightbulbs are associated in collection to a 120 V source, which is brighter? Explain.

Answer: Bulbs associated in collection each take it the exact same current. Strength is additionally given by the equation P = I2R. V the very same current, the bulb with the bigger resistance will certainly dissipate much more power. Since the 60 W bulb has actually the bigger resistance, it will be brighter.

8. Location the brightness the the adhering to bulbs, with 1 gift the brightest and 4 being dimmest. Justify your answer with an explanation and/or a calculate in the room below.

Calculate the strength dissipated by each bulb.

Answer: ___60 W bulb connected to 50 V source


___100 W bulb connected to 50 V source


In series: The identical resistance that the 2 bulbs in series is 380W. When connected to 120 V, the existing in the circuit is

. This same current flows with both bulbs.

___ 60 W pear in series with 100 W bulb and also 120 V source


___ 100 W bulb in collection with 60 W bulb and 120 V source


Now rank follow to power dissipated:

4 (10 W) 60 W bulb connected to 50 V source2 (18 W) 100 W bulb connected to 50 V source1 (25 W) 60 W pear in collection with 100 W bulb and 120 V source3 (14 W) 100 W bulb in series with 60 W bulb and also 120 V source

9. Describe briefly why, in her house, a 100 W pear will always be brighter than a 60 W bulb.

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Answer: In a house, all electric outlets are associated in parallel come 120 V. Bulbs that you to buy in the store space rated for use on a standard family 120 V circuit. So if friend plug your lamps right into a standard outlet, you always use the bulbs at their rated voltage and also thus at their rated power. A 100 W pear at home will always dissipate an ext power 보다 a 60 W bulb and also so will always be brighter.