1.An electric bulb tated for 200 W and
100 V is connected to a circuit having a
200 V supply. The resistance 'R' that
must be put in series with the bulb, so
that the bulb draws 200 W is
(A) 50ohm
(B) 100ohm
(C) 150ohm
(D) None of these
Answers
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Answer:
a) 50 ohm
Explanation:
Rated power of the bulb = 200 W (Given)
Operating voltage = 100 V (Given)
Current drawn by the bulb = power/voltage = 200/100 = 2A
Resistance = Voltage/current = 100/2 = 50 Ω
Thus, when the bulb will be connected in 200 V supply, it needs to be ensured that by connecting additional resistance. the current passing through this bulb is 2A.
Total resistance required to get 2A from 200 V = 200/2 = 100 Ω
Since the resistance of bulb is 50 Ω , therefore we need to add additional 50 Ω resistance in series so that bulb draws 200W
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