The minimum number of identical bulbs of rating 4V; 6W, that can work safely with desired brightness, when connected in series with a 240 V mains supply is:
(a) 20
(b) 40
(c) 60
(d) 80
Correct Answer : Option (c) 60
More Questions : An electric bulb is rated 220 V, 11W. The resistance of its filament when it glows with a power supply of 220 V is :
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