मराठी

The Unit for Expressing Electric Power Is: (A) Volt (B) Joule (C) Coulomb (D) Watt - Science

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प्रश्न

The unit for expressing electric power is: 

(a) volt
(b) joule
(c) coulomb
(d) watt

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उत्तर

(d) watt
Watt is the unit of electric power.

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पाठ 1: Electricity - Exercise 7

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संबंधित प्रश्‍न

The diagram below shows a circuit containing a lamp L, a voltmeter and an ammeter,. The voltmeter reading 3 V and the ammeter reading is 0.5 A. 

  

 What is the resistance of the lamp?
 What is the power of the lamp?


Which of the following is the most likely temperature of the filament of an electric light bulb when it is working on the normal 220 V supply line?

(a) 500°C
(b) 1500°C
(c) 2500°C
(d) 4500°C


Two lamps, one rated 220 V, 50 W and the other rated 220 V, 100 W, are connected in serieswith mains of 220 V. Explain why does the 50 W lamp consume more power


Calculate the current through a 60 W lamp rated for 250 V. If the line voltage falls to 200 V, how is the power consumed by the bulb affected?


Two bulbs are rated 60 W, 220 V and 60 W, 110 V respectively. Calculate the ratio of their
resistances


An electric toaster draws 8 A current in a 220 V circuit. It is used for 2 h. Find the cost of
operating the toaster if the cost of electrical energy is Rs. 4.50 per kWh.


A geyser is rated 1500 W, 250 V. This geyer is connected to 250 V mains. Calculate:
(i) the current drawn
(ii) the energy consumed in 50 hours, and
(iii) the cost of energy consumed at Rs. 4.20 per kWh


An immersion heater rated 1000 W, 220 V is used to heat 0.01 m3 of water. Assuming that the power is supplied at 220 V and 60% of the power supplied is used to heat the water, how long will it take to increase the temperature of the water from 15°C to 40°C?


Define potential difference between two points.

Distinguish between electric power and electrical energy. State their units. Give the other name of kWh.

A dynamo converts one from of energy into another. Name the two forms of energy.

Which cable, one rated 15A and the other rated 5A will be thicker? Give a reason.


State three factors on which the heat produced in a metallic wire due to passage of current in it depends.


State two advantages of filling an inert gas in an evacuated electric filament lamp.


A family uses a light bulb of 100W, a fan of 100W, and a heater of 1000W, each for 8 hours a day. If the cost of electricity is Rs. 2 per unit, what is the expenditure to the family per day, on electricity?


An electric lamp A of 40 W and another electric lamp B of 100 W are connected to 220 V supply. Calculate the ratio of their filament resistances?


The equation I2R seems to suggest that the rate of heating in a resistor is reduced if resistance decreases, whereas equation P = V2/R suggests just the opposite. How do you reconcile this problem?


Find the cost of operating an electric toaster for two hours if it draws 8 A current on a 110 volt circuit. The cost of electrical energy is Rs. 2.50 per kWh.


Unit of electric power may also be expressed as:


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