Answer:
(a) 1.35 x 10^6 Joule
(b) 321.45 Kcal
Explanation:
Energy consumed in 1 hour = 270 kJ
So, Energy consumed in 5 hour = 270 x 5 = 1350 kJ
(a) Energy in joules = 1350 x 1000 J = 1.35 x 10^6 J
(b) 4.2 Joule = 1 calorie
So, 1.35 x 10^6 Joule = 1.35 x 10^6 / 4.2 = 0.32 x 10^6 Calorie
= 0.32 x 1000 Kcal = 321.45 Kcal
The electrical energy consumed by the lightbulb is 1..35 x 10⁶J or 322.65 kcal.
The electrical energy consumed by the lightbulb is the product of power and time of energy consumption.
E = Pt
1 h ------------------- 270 kJ
5 h -------------------- ?
= 5 x 270 kJ
= 1,350 kJ
= 1.35 x 10⁶ J.
1 kJ ---------------- 0.239 kcal
1,350 kJ ------------ ?
= 1,350 x 0.239
= 322.65 kcal.
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