Question

Hello Guys

Please give the solution of this 10 standard question

Q) 2 lamps, one rated 100W at 220V and the other 200W at 220V are connected

(I) In series
(II) In parallel to electric main supply of 220V.

Find the current drawn in each case.

Answer 1

Answer:

Resistance R of each lamp from given power P and operating voltage V is obtained from the relation,

P = ( V2 / R ) ....................... (1)

Hence resistance of 100W, 220 V lamp = (220×220)/100 = 484 Ω

Resistance of 200W, 220 V lamp = (220×220)/200 = 242 Ω

when lamps are connected in series , equivalenet resistance = 484+242 = 726 Ω

Hence current drawn by lamps that are connected in series = 220/726 = 0.3 A

When lamps are connected in parallel, each lamp draws current independenly as per its wattage.

Current drawn by 100 W lamp = 100/220 = 0.45 A

Current drawn by 200 W lamp = 200/220 = 0.91 A

Hence total current drawn by lamps when they are connected in parallel = 0.45+0.91 = 1.36 A

Answer 2

Explanation:

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