Question

solve my question solve the question..​

Answer 1

We know the Formula,

R = V²/P

Now, For First Lamp, V = 220 V, and P = 100 W.

∴ R₁ = 220²/100

∴ R₁ = 484 Ω

For Second Lamp, V = 220 V, P = 200 W,

∴ R₂ = 220²/200

∴ R₂ = 484/2

∴ R₂ = 242 Ω

(i) When they are connected in series,

R = R₁ + R₂ = 484 + 242

R = 726 Ω

Using Ohm's law,

V = IR

∴ 220 = I × 726

∴ I = 0.3030 A.

(ii) When they are connected in Parallel,

1/R = 1/R₁ + 1/R₂

∴ 1/R = 1/484 + 1/242

∴ R = 161.3 Ω

Again using the Ohm's law,

I = V/R = 220/161.3

I = 1.36 A.

Answer 2

QUESTION⤵️

two lamps one rated 100 watt at 220 volt and the other 200 watt at 220 volt are connected (i.) in series and (ii.) in parallel of electric main supply of 220 volt. find the current drawn in each case.

ANSWER ⤵️

resistance R of each lamp from given power p and operating voltage v is obtained from the relation,

$p = \frac{ {v}^{2} }{r}$

-----------------eq.(1)

Hence,

resistance of 100W, 220V lamp=

$\frac{220 \times 220}{100} = 484ohm$

resistance of 200W and 220 V lamp=

$\frac{220 \times 220}{200} = 242ohm$

when lamps are connected in series,

equivalent resistance= 484+242= 726ohm

Hence, current drawn by lamps that are connected in series =

$\frac{220}{726} = 0.3A$

when lamps are connected in parallel, each lamp draws current independently as per its wattage.

current drawn by 100W lamp=

$\frac{100}{220} = 0.45A$

current drawn by 200W lamp =

$\frac{200}{220} = 0.91A$

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

$\longrightarrow\pink{1.36A}$

$\huge\mathtt\star\red{hope \: it \: helps}\star$