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If two bulbs of `25 W and 100 W` rated at `220 V` are connected in series across a `440 V` supply, will both the bulbs fuse ? If not which one ?A. 25 W bulbB. 100 W bulbC. both of theseD. none of these |
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Answer» Correct Answer - a Resistance of one bulb, `R_(1) = (220)^(2)//25` ohm Resistance of other bulb, `R_(2) = (220)^(2)//100` ohm Total resistance when two bulb are in series will be `R = (220)^(2)//25 + (220)^(2)//100 = (220)^(2)//20 Omega` Given `I = (V)/(R ) = (440)/((220)^(2)//20) = (2)/(11)` Amp Potential difference across `25W` bulb `= IR_(1) = ((220)^(2))/(25) xx (2)/(11) = 352V` Potential difference across `100W` bulb `= ((220)^(2))/(100) xx (2)/(11) = 88 V` The bulb of `25` watt will be fixed become if can tolerate only `220V` while the voltage across it is `352V` |
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