Advertisements
Advertisements
प्रश्न
What is the resistance, under normal working conditions, of an electric lamp rated at '240 v, 60 W' ? If two such lamps are connected in series across a 240 V mains supply, explain why each one appears less bright.
Advertisements
उत्तर
Given voltage, V = 240 V
Power, P = 60 W
As P = `"V"^2/"R"`
∴ R = `(240)^2/60`
= 960 Ω
I = `"P"/"V"` = 0.25 A
When one lamp is connected across the mains, it draws 0.25 A current, while if two lamps are connected in series across the mains, current through each bulb becomes
`(240 "V")/((960 + 960) Omega) = 0.125 "A"`
(i.e., current is halved), hence heating (= I2Rt) in each bulb becomes one-fourth, so each bulb appears less bright.
APPEARS IN
संबंधित प्रश्न
In a household electrical circuit, the appliance are connected in ............with the mains.
What is an electric meter? Where is it fixed in our house?
For which unit do we pay our electricity bill?
Name the unit in which you pay the cost of your electricity bill. How is it related to joule?
Draw a labelled diagram with the necessary switches to connect a bulb, a fan and a plug socket in a room with the mains. In what arrangement will you connect them to the mains?
An electric iron of power 1.5 kW is used for 30 minutes to press the clothes. Calculate the electrical energy consumed in
- kilowatt-hour
- joule.
Assuming the electric consumption per day to be 12 kWh and the rate of electricity to be? 6.25 per unit, find how much money is to be paid in a month of 30 days?
In a premise 5 bulbs each of 100 W, 2 fans each of 60 W, 2 A.Cs each of 1.5 kW is used for 5 h per day. Find:
- Total power consumed per day,
- Total power consumed in 30 days,
- Total electrical energy consumed in 30 days.
- The cost of electricity at the rate of ₹ 6.25 per unit.
Two lamps, one rated 220 V, 50 W and the other rated 220 V, 100 W, are connected in series with mains of 220 V. Explain why does the 50 W lamp consume more power.
An electrical appliance is rated as 60 W – 150 V.
How much current will flow through the appliance when in use?
