Question

4. Power Consumption in Automotive Headlight Bulbs Suppose an automobile is designed with two headlights which each consume 100 W. The bulbs are powered by a 12 V electrical system. (a) Calculate the resistance of each bulb, assuming that the voltage across each bulb is 12 V and assuming that each bulb consumes 100 W. correct: (b) Suppose that the bulbs are connected incorrectly. that is, suppose they are connected in series rather than in parallel. 12 V P= 100 W Find the power consumed by each bulb in this case. Note: This can be answered without solving (a). incorrect: 12 V (c) Finally, suppose that the bulbs are replaced with high-efficiency LED headlights, which only consume 10 W each when they are connected to the battery in parallel (as in the "correct" circuit.) Find the current through each LED unit.

Answer 1

P:100w 12V Lek sey Resistance g each beelb is R. consumed 0 so power RE2% = 1.4401 Ans b) P=2 bells are connected Pin correctly ce. Pour Now Suppose series Now Power consumed by each beelb =12R I = current 2x144 - 4.16 Amp - Power consumed by each bulb= 4:16²x1.44 R = 25W Ans replaced by high efficiency LED bulb C) Now bulb are V.T. Power consumed P. V:120, , ?: = 0.83 Amp. current through each LED bulb