# Two bulbs A and B are rated 100w-120v and 10w-120v. they are connected across a 120v source in series. which will consume more energy

2
by dkavyasri13

2015-05-27T11:31:30+05:30

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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.

pick as best if helps
2015-05-27T11:41:45+05:30
given:
bulb A is rated 100w-120 v
bulb B is rated 10w-120v

required :

Which bulb will consume more energy ?

solution :

Let's find out the resistances of each bulb from the data given:

R1 = U1^2 /

⇒P1 = 120^2 / 100 = 144 Ohm

R2 = U2^2 / P2 = 120^2 / 10 = 1440 Ohm

Let's  use P = I^2 * R for each bulb and find out if it is greater.

P1 = (120 / (144
+ 1440))^2 * 144 = 0.8264 W

P2 = (120 / (144  + 1440))^2 * 1440 = 8.2644
W.

Answer: second bulb will consume more energy
.

hope helped u dear frnd @ :-)

thank Q

plzzzz pick my answer as the best one