Q24 of 41 Page 461

Bulb is rated at 200 V, 100 W. Calculate its resistance. Five such bulbs are lighted for 4 hours daily. Calculate the units of electrical energy consumed per day. What would be the cost of using these bulbs per day at the rate of Rs. 4.00 per unit?

We know that for an electric appliance


Resistance will be given as



Now, here


P = 100 W


V = 200 volts


So, R =


R =


Thus, resistance of the bulb is R = 400 Ω


Now, electric energy consumed will be


E = power of each unit × time.


⇒ E = p × t.


Here


P = 100 W


t = 4 hours


So,


E = 100 x 4 = 400 Watt per hour


Dividing by 1000 to convert into Kilo Watt per hour


E = kWh


Electrical energy consumed is kWh


The total cost of electricity = total unit of energy consumed x cost per unit =


Cost = 0.4kWh x 4 Rs/kWh = Rs1.6


Thus, total cost (daily) = Rs. 1.6


More from this chapter

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23

Identify the type of combination in which R1 and R2 are connected in the given circuit diagram.

 23

Find the effective resistance of the combination.

 25

When a high resistance voltmeter is connected directly across a resister its reading is 2 V. An electric cell is sending the current of 0.4A, (measured by an ammeter) in the electric circuit in which a rheostat is also connected to vary the current.

Draw an equivalent labelled circuit for the given data.

 25

When a high resistance voltmeter is connected directly across a resister its reading is 2 V. An electric cell is sending the current of 0.4A, (measured by an ammeter) in the electric circuit in which a rheostat is also connected to vary the current.

Find the resistance of the resister.