Question

A bulb is rated at 330 volt / 110 watt. What do you think is its resistance? Three mm
such bulb burn for 5 hours. What is the energy consumed? Calculate the cost in
rupees if the rate is 75paise per unit

Answer 1

Answer:

R=110ohms,E=

Explanation:

Since P=VI so 110W =330V/I

So I=330V/110W I = 3A

V=IR. So, R=V/I. R=330V/3A. R=110ohms

Now, Energy = 3×5×110=1650J

now in kwh, P=1650÷1000 P=1.65Kwh or 1.65 unit

so cost =75×1.65p =123.75P in 1 day.

Answer 2

Answer:

Answer:

Resistance of 1 bulb = 990Ω

Total cost of energy consumed = Rs 1.2375

Explanation:

Power = $\rm\frac{Work \: \: Done}{ Time}$

Work Done = Energy

Therefore ,

Power = $\rm\frac{Energy}{ Time}$

Energy = VIt

Time = t

Power = $\rm\frac{V \: I \: \cancel{t}}{ \cancel{t}}$

Power = VI

According to the question ,

V = 330 V

P = 110 W

t = 5 hrs

Number of bulbs = 3

Cost of 1 unit of Energy = 75 paise

P = VI

I = P/V

I = $\rm{\frac{ \cancel{110}}{ \cancel{330} } \: A}$

I = $\rm \frac{1}{3} \: A$

By Ohm's Law

V = IR

R = V/I

R = $330 \div \frac{1}{3}$ Ω

R = $330 \times 3$ Ω

R = 990 Ω

Therefore , resistance of 1 bulb is 990 Ω .

Energy = VIt

E = VIt

E = $330 \times \frac{1}{3} \times 5$ Wh

E = 550 Wh

Therefore , energy consumed by 1 bulb is 550 Wh .

Energy consumed by 3 bulbs = 3 X Energy consumed by 1 bulb

Energy consumed by 3 bulbs = 3 X 550 Wh

Energy consumed by 3 bulbs = 1650 Wh

1 kWh = 1000 Wh

1 Wh = $\frac{1}{1000}$ kWh

1650 Wh = $\frac{1650}{1000}$ kWh

1650 Wh = 1.65 kWh

Therefore , energy consumed by 3 bulbs is 1650 Wh or 1.65 kWh .

1 Rupee = 100 paise

1 paise = $\frac{1}{100}$ Rupee

75 paise = $\frac{75}{100}$ Rupee

75 paise = Rs 0.75

1 unit = 1kWh

Cost of 1 unit of Energy = Rs 0.75

Cost of 1 kWh of Energy = Rs 0.75

Cost of 1.65 kWh of Energy = Rs 0.75 X 1.65

Cost of 1.65 kWh of Energy = Rs 1.2375

HOPE IT HELPS YOU !

THANKS !