Question

Assume 40% of the input electricity power is wasted as heat in an incandescent light bulb. (This value is higher in real life, but we will use this estimate.)
1. If you have 10 incandescent bulbs in your apartment, calculate the energy wasted as heat per week. (Each bulb is 75 W (J/s), and your lighting duration is 6 hours per day.)

Answer 1

Answer:

45360 kJ

Explanation:

We can calculate energy by multiplying the power by time:

E = P * t

Each bulb has a power rating of 75W.

In 6 hours (3600 seconds) of each day, the energy exerted by each bulb will be:

E = 75 * 6 * 3600 = 1620000J

10 bulbs will therefore exert:

10 * 1620000 J = 16200 kJ

In a week, the energy exerted will be:

16200000 * 7 = 113400 kJ

Since 40% of this energy is wasted as heat, therefore, the amount of energy wasted as heat is:

40/100 * 113400000 = 45360000 = 45360 kJ