Question

34. An electric refrigerator rated 400W and an electric bulb rated 100W. Operates 10 hours day. What is the cost of the energy to operate it for 10 days at Rs 8.00 per kWh?​

Answer 1

Answer:

Rs. 400

Explanation:

Power consumed by refrigerator= 400W

Power consumed by bulb = 100W

Total power consumed = 400+100 = 500W = 0.5 kW

total operating time = 10 days at the rate 10hrs per day

                                 = 10×10 hr

                                 = 100 hr

Total energy consumed = Power × time = 0.5×100 = 50kWh

Price = Rs. 8.00 per kWh

Total cost = 50 × 8 = Rs. 400

Answer 2

Answer:

Given :-

• An electric refrigerator rated 400W and an electric bulb rated 100W.
• The energy to operate it for 10 days at Rs 8.00 per kWh.

To Find :-

• What is the cost of the energy.

Formula Used :-

$\clubsuit$ Energy Formula :

$\bigstar \: \: \sf\boxed{\bold{Energy =\: Power \times Time\: Taken}}\: \: \: \bigstar$

Solution :-

First, we have to find the total power consumed :

Given :

• Power consumed by Refrigerator = 400 W
• Power consumed by Electric Bulb = 100 W

According to the question by using the formula we get,

$\footnotesize \implies \sf\bold{\underline{Total\: Power =\: Power_{(Refrigerator)} + Power_{(Electric\: Bulb)}}}$

$\implies \sf Total\: Power =\: 400 + 100$

$\implies \sf\bold{Total\: Power =\: 500\: W}$

Hence, the total power is 500 W .

Now, we have to find the energy consumed :

Given :

• Power = 500 W
• Time Taken = 10 hours

According to the question by using the formula we get,

$\implies \sf\bold{\underline{Energy =\: Power \times Time\: Taken}}$

$\implies \sf Energy =\: 500 \times 10$

$\implies \sf\bold{Energy =\: 5000\: Wh}$

By convert the energy Wh into kWh we get,

$\implies \sf Energy =\: 5000$

$\implies \sf Energy =\: \dfrac{5\cancel{000}}{1\cancel{000}}\: kWh$

$\implies \sf Energy =\: \dfrac{5}{1}$

$\implies \sf\bold{Energy =\: 5\: kWh}$

Hence, the energy consumed is 5 kWh .

Now, we have to find the energy consumed in 10 days :

$\mapsto$ Energy consumed in 1 days = 5 kWh

So, the energy consumed in 10 days will be :

$\leadsto \sf 5 \times 10$

$\leadsto \sf\bold{50\: kWh}$

Now, we have to find the total cost of the energy :

$\mapsto$ Cost of 1 kWh = Rs 8.00

So, cost of 50 kWh will be :

$\dashrightarrow \sf 50 \times 8.00$

$\dashrightarrow \sf\bold{Rs\: 400}$

$\therefore$ The cost of energy is Rs 400 .