Table 1 DMM reading an observed bulbs\' brightness for the cireuits in Fig 4 Sou
ID: 2303570 • Letter: T
Question
Table 1 DMM reading an observed bulbs' brightness for the cireuits in Fig 4 Source voltage DMM Current Current Observed reading through through brightness power each bulb Cases Eich 4 Fig. 4C) Fig. 4(d) but with one 433 light bulb removed Questions on Measurement #1 : 1. Is the current through the power supply and each bulb (in Table 1) increasing or decreasing with increasing the number of bulbs from Fig. 4 (a) to Fig. 4 (d)? Why? Is there any correlation between the current through each bulb and the observed bulbs' brightness listed in Table 1? If yes, is the correlation consistent with P-IV R? 2. 3. Are the lights at your home connected in series? Why? Measurement#A Light bulbs in parallel connectionExplanation / Answer
Answer-1: Yes, current through the power supply and each bulb is DECREASING with INCREASING the number of bulbs and that is due RESISTANCE.
As we know from elementary electronics that if N resistances are connected in series, the total resistance is the sum of individual resistances,
R =R1 + R2 +........+RN
So incresing the number of bulbs increases the resistance, but according to ohm's law,
Voltage across the source is related to the resistance by,
V = IR
So increasing the R results in a dip in current I.
So we have the following rule :"when the bulbs are connected in series, increasing the number of bulbs results in current through them".
Answer-2. Yes, there is indeed a relation between the current through each bulb and the observed brightness of the bulb.The correlation is consistent with power law which is:
P = I2R
For a given R for a particular bulb, the consumption decreases as the square of the current. So decreasing the current decreases the brightness of the bulb.
Answer-3. No! Lights in our houses are not connected in series, instead, they are connected in parallel. And it is so for the following reasons:
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