An electric bulb is marked 100 W , 230 V. If the supply voltage drops to 115 V, what is the heat and light energy produced by the bulb in 20 min ?

Question

An electric bulb is marked 100 W , 230 V. If the supply voltage drops to 115 V, what is the heat and light energy produced by the bulb in 20 min ? (A) 20000 J (B) 25000 J (C) 30000 J (D) 35000 J

Tardigrade Admin · Accepted Answer

R=(V2/P)=((230)2/100)=529 Ω When the voltage drops to 115 V, heat and light energy produced by the bulb in 20 min is given by W=(V2/R) t=((115)2/529) × 20 × 60=30000 J

Q. An electric bulb is marked $100 W, 230 V$ . If the supply voltage drops to $115 V$ , what is the heat and light energy produced by the bulb in $20 min$ ?

$20000 J$

$25000 J$

$30000 J$

$35000 J$

$R = \frac{V ^{2}}{P} = \frac{( 230 ) ^{2}}{100} = 529Ω$
When the voltage drops to $115 V$ , heat and light energy produced by the bulb in $20 min$ is given by
$W = \frac{V ^{2}}{R} t = \frac{( 115 ) ^{2}}{529} \times 20 \times 60 = 30000 J$

Q. An electric bulb is marked 100W,230V. If the supply voltage drops to 115V, what is the heat and light energy produced by the bulb in 20min ?

20000J

25000J

30000J

35000J