Question

An electric lamp is marked 100W,220V' what do u understand by this? What current is taken by the lamp when it is connected to a 220v mains supply? What is the resistance of the lamp​

Answer 1

$\red{\odot}$ Correct Question :

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• $\textsf{An electric lamp is marked 100 W, 220 V. It means that the electric lamp will consume 100 joule of energy per second when connected to a 220 V supply.}$

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$\green{\odot}$ Required Solution :

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• $\textsf{Given that the electric lamp is connected to a exactly 220 V mains supply. }$

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$\purple{\odot}$ So, We have

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• $\textsf{Potential difference, V = 220 v}$

• $\textsf{Power, P = 100 W}$

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• ⇒ $\textsf{P = V I}$

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$\pink\bigstar$Where,

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• $\textsf{P = Power}$

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• $\textsf{V = Potential difference}$

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• $\textsf{I = Current}$

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• $\textsf{⇒ 100 = 220 × I}$

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• $\textsf{⇒ 10/22 = I}$

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• $\textsf{⇒ 5/11 = I}$

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• $\textsf{⇒ I = 5/11 A}$

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• $\textsf{Potential difference, V = 220 v}$

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• $\textsf{Current, I = 5/11 A}$

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$\mathfrak{✴\;So, \;Resistance \;of \;the\; electric \;lamp \;can\; be calculated \;as,}$

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• $\blue\bigstar$$\textsf{⇒ V = I R}$

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$\red\bigstar$Where,

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• $\blue\bigstar$$\textsf{R = Resistance}$

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• $\textsf{⇒ 220 = 5/11 × R}$

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• $\textsf{⇒ 220 × 11/5 = R}$

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• $\textsf{⇒ 44 × 11 = R}$

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• $\textsf{⇒ R = 484 Ω}$

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$\mathfrak{✴\;Hence,\; When\; the\; electric \;lamp\; is\; connected\; to\; a\; 220\; v\; mains\; supply,}$

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• $\orange\bigstar$$\textsf{Current drawn = 5/11 A}$

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• $\green\bigstar$$\textsf{Resistance = 484 Ω}$

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Answer 2

$\Huge\mathbf\colorbox{orange}{{\color{black}{☆ANSWER☆}}}$

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$\huge\bf\underline{\underline{\orange{GIVEN :}}}$

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$\orange\bigstar$ An electric lamp is marked 100W, 200V.

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$\huge\bf\underline{\underline{\orange{TO \: FIND :}}}$

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$\orange\bigstar$ What do you understand by this ?

$\orange\bigstar$ What current is taken by the lamp when it is connected to a 220 V mains supply ?

$\orange\bigstar$ What is the resistance of the lamp ?

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$\huge\bf\underline{\underline{\orange{SOLUTION :}}}$

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$\orange\bigstar\bf{P = Power}$

$\orange\bigstar\bf{V = Potential \: Difference}$

$\orange\bigstar\bf{I = Current}$

$\bf{→100 = 220 \times I} \\ \\ \bf{→ \frac{10}{22} = I} \\ \\ \bf{→ \frac{5}{11} = I} \\ \\ \bf{→ I = \frac{5}{11} A}$

$\orange\bigstar$ We will calculate the resistance of the electric lamp as V = I R,

$\bf{→220 = \frac{5}{11} \times R} \\ \\ \bf{→220 \times \frac{11}{5} = R } \\ \\ \bf{→44 \times 11 = R} \\ \\ \bf{→R = 484 \: Ω}$

$\boxed{{\sf\orange{Hence, \: 5/11 A \: current \: is \: taken \: by \: the \: lamp \: when \: it \: is \: connected \: to \: a \: 220 \: V \: mains \: supply.}}}$

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$\boxed{{\sf\orange{Hence, \: the \: resistance \: of \: the \: lamp \: is \: 484 \: Ω}}}$

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Hope it Helps Buddy ♥️