why can we use P=VI in the question electric bulb base generator is rated 220 volts and 100W when it is operated on 110v what will be its power consumed?

Correct answer: P₂ = 25 W

Explanation:

Given: voltage V₁ = 220 V, power P₁ = 100 W, V₂ = 110 V, P₂ = ?

The formula for calculating power is:

P = V · I

We will include in the story and ohm's law:

I = V/R

We will replace the current in the expression for power

P = V · V/R = V²/R ⇒ R = V²/P

We will first calculate the electrical resistance of the bulb which is a constant in the electrical circuit

R = V₁²/P₁ = 220² / 100 = 48,400 / 100 = 484 Ω

Power consumption of bulb connected to 110 V is:

P₂ = V₂²/R = 110²/484 = 12,100/484 = 25 W

P₂ = 25 W

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