Question

If a bulb is marked 220volt and 40watt. Calculate the current flowing through the bulb and it's resistance

Answer 1

Answer:

Power = Potential Difference × Current

According to the question,

• Power = 40 W
• Potential Difference = 220 V

⇒ Current = Power / Potential Difference

⇒ Current = 40 W / 220 V

⇒ Current = 0.18 A

Therefore Current flowing through the bulb is 0.18 A.

⇒ Power = ( Potential Difference )² / Resistance

⇒ 40 = ( 220 )² / R

⇒ R = (220)² / 40

⇒ R = 48400 / 40 = 1210 ohms

Therefore the resistance offered by the bulb is 1210 ohms.

Answer 2

$\bf\large\underline{Answer:}$

Current flowing through the bulb is 0.18 A

Resistance of the bulb is 1210 ohms.

$\bf\large\underline{Explaination:}$

Given :-

Potential difference = 220 volt

Power = 40 watt

To find :-

• Current flowing through the bulb
• Resistance of the bulb

Solution :-

To calculate the current (I),

=> Power = Current × Potential Difference

=> 40 = Current × 220

=> $\bf\large\frac{40}{220}$ = Current

=> $\bf\large\frac{4}{22}$ = Current

Current flowing through the bulb is 0.18 A

Now we will calculate the resistance.

=> Power = $\bf\large\frac{(Potential\:Difference)^2}{Resistance}$

=> 40 = $\bf\large\frac{(220)^2}{Resistance}$

=> 40 = $\bf\large\frac{48400}{Resistance}$

=> Resistance = $\bf\large\frac{48400}{40}$

=> Resistance = $\bf\large\frac{4840}{4}$

=> Resistance = 1210 ohms