Question

Find the energy consumed in kWh by 10 bulb of 60 W each in 5 hours.

Answer 1

Step 1: Given data:

Power of each bulb is P = 60 W = 60 J/s.

Time duration is t = 5 hours = (5 hours) x (3600 sec/hour) = 18000 sec.

Number of bulbs is n = 10.

Step 2: Finding the energy consumed by each bulb:

Power = $\frac{\mathrm{energy}}{\mathrm{time}}$

Energy = power x time

E = p x t

Where E is the energy consumed by each bulb.

Substituting the known values,

E = (60 J/s) x (18000 s)

E = 1080000 J

Step 3: Finding the total energy consumed by all the bulbs:

E' = E x n

Where E' is the total energy consumed.

E' = (1080000 J) x 10

E' = 10800000 J = 10.8 x 10⁶ J

Step 4: Finding the total energy in kWh:

Since, 1 unit = 1 kWh = 3.6 x 10⁶ J

In terms of units, 10.8 x 10⁶ J is equivalent to,

Energy in kWh (units) = $\frac{10.8x{10}^6}{3.6x{10}^6}$ = 3 kWh.

Hence, energy consumed is 3 kWh.