Question

How much energy expressed in units of food Calories (that is, kilocalories) is required to operate a 97.097.0 W light bulb for 12.012.0 hours?

Answer 1

Answer:

1.164 kWh = 1001.53 kCal

Explanation:

Given that,

Power required to operate, P = 97 W

Time, t = 12 h

To find,

Energy required to operate.

Solution,

The electric power of an object is given by the energy required per unit time. It is given by :

$P=\dfrac{E}{t}$

$E=P\times t$

$E=97\ W\times 12\ h$

E = 1164 Wh

or

E = 1.164 kWh

Since, 1 kWh = 860.421 kCal

So, 1.164 kWh = 1001.53 kCal

So, the energy required to operate is 1001.53 kCal. Therefore, this is the required solution.

Answer 2

Answer:

997.7 kcal

Explanation:

Power, P = 97 W

Time, t = 12 hours = 12 x 60 x 60 s = 43200 s

Energy, E = Power x time

E = 97 x 43200

E = 4190400 J

E = 4190.4 kJ

1 cal = 4.2 J

So,

E = 997.7 kcal