Question

Two bulbs A and B are rated 100W,120V and 10W,120V respectively. They are connected across a 120V source in parallel

Answer 1

GIVEN ;-

⇒ Bulb A is rated as = 100 w - 120 v

⇒Bulbs B is rated as = 10 w - 120 v

⇒ Two bulbs are connected across a source in series of = 120 v


TO FIND ;-


⇒ Which will consume more energy ?


SOL ;-


⇒ In the bulb A -  
                     
                      ⇒ Volts = 120 v

                      ⇒ Power = 100 w

⇒In the bulb B-

                    ⇒ Volts = 120 v

                    ⇒ Power = 10 w


Now let us find the resistance of the two bulbs -


             ⇒ R = V² / P


Let us find the resistance for the bulb A-

             ⇒ Bulb A ( R ) =  120 ² / 100 =  144 ohm


             ⇒ Bulb B ( r ) =  120 ² / 10  = 1440 ohm



Now we got the resistance for both the bulbs.

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To find the series combination , we need to use the below formula to find out it -


⇒ R = R₁ + R₂ =
 
      =  144 + 1440

      = 1584 ohm is the resistance in series combination.



So 10 watts bulb consume more energy because uses less power and also the amount o current flowing is less . Remember the formula -  P=I x E.