Question

Two bulbs A andB are rated 100 W, 120V and 10W, 120V respectively. They are connected in series across a 120 V source. Find the current in each bulb

Answer 1

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. 

Answer 2

Your question

Two bulbs A andB are rated 100 W, 120V and 10W, 120V respectively. They are connected in series across a 120 V source. Find the current in each bulb?

Hii

you are welcome in my ans

Given

Power of bulb A and B = 100w and 10w

potential in both A and B bulb = 120v and 120v

voltage source = 120v

Clue

They are in series

Now

we know that

p = V^2 /R

R = V^2/p

for bulb A

R = 120*120/100= 144ohm

so

current = v/r= 120/144= 10/12= 5/6 ampere

for bulb B

R = 120*120/10= 1440ohm

i = V/R = 120/1440 = 1/12 ampere

mate it is not possible that two resistance are in parallel having same potential difference may be it's wrong questions then also I tried .